APA 2014-2: Against causal reductionism

relativityby Massimo Pigliucci

Second report from this year’s meeting of the Eastern Division of the American Philosophical Association. This session, under the general heading of philosophy of science, was actually constituted of just one talk, entitled “Against causal reductionism” and delivered by Chris Weaver (Rutgers University) (the session was chaired by Michael Hicks, Rutgers University).

As you’ll see from my interspersed and final comments, I actually disagree with the author’s main thesis, and even the way he goes about defending it. But the talk did stimulate my neuronal firing, and I hope it will generate some thoughtful discussion here, as well as provide another example of what professional philosophers do at their daily job.

Weaver began by observing that the consensus view in physics is that the universe began in a very unusual state of very low entropy, but maintains that the characterization of such initial state as “unusual” is based on the highly questionable principle of indifference [1] and is otherwise difficult to defend. I don’t really have a bone to pick in that particular fight, and it honestly wasn’t clear to me how exactly this related to the main topic of the talk, causal reductionism, but that’s where we are going next.

Weaver thinks that causal reductionism is based on an unsound argument from physics. Causal reductionism – in this context – is the view that causal interactions reduce to non-causal facts, that they are nothing above and beyond lawfully related events, where natural laws themselves are not “causal.” (Of course, there is a huge literature on the very concept of causation itself, but we’ll leave that for another day. [2])

Causal reductionism, according to Weaver, is not implied by empirical analyses of causation but depends instead on the following “argument from physics”:

P1) Physical science only requires natural law and physical history (no causation)
P2) If 1, then causal reductionism holds
C) Causal reductionism holds

Therefore, according to Jonathan Schaffer, among other authors, “causation disappears from sophisticated physics.” Weaver doesn’t buy it, and proposes to attack the first premise above, by arguing that there is a distinction between the formalism and the interpretation of any given theory T, and that while some particular physical theory T lacks the formalism of causation, any sensible interpretation of T will have to include causal talk.

Take the idea of a gravitational field in the general theory of relativity (henceforth, GTR). While the formalism of the theory (i.e., the equations) doesn’t include any talk of causes, the field itself has to be interpreted – according to Weaver – as having causal properties: if gravitation is the conformation of space-time itself, then obviously it has causal properties.

GTR is based on four principles: relativity, general covariance, finitude of the speed of light, and equivalence [3]. Weaver maintains that the principle of equivalence (between gravitational and inertial mass) includes language concerned with the effects of gravitation, i.e., it is framed by using talk of causality. Even when it is not expressed using causal language per se, the principle is usually accompanied by language that implies causal notions (for instance in Sean Carroll’s 2003 textbook [4]). Indeed, Einstein himself understood the principle of equivalence in causal terms, which Weaver demonstrated by using a number of direct quotations.

So, the idea is that although the field equations of GTR do not explicitly include any causal talk, one cannot avoid but interpret them as telling us about the behavior of the gravitational field, including, therefore, its (causal) effects on the motion of objects and free particles.

Weaver appropriately quoted a number of experts on GTR confirming his interpretation that Einstein did talk of the theory in interpretive causal terms, whenever he was discussing how the theory accounts for the inertial motion of bodies.

(At this point in the talk I had the perhaps obvious thought that while all of the above is fine, GTR is still a classical theory, and that causal talk – and hence Weaver’s approach – still break down when we get to quantum mechanics, or to a future quantum theory of gravity. Turns out the author himself dealt with this objection toward the end of his talk, not at all in a satisfactory manner, I think.)

Yet another example of causation within GTR is the theory’s prediction of gravitational waves, which do causally affect both fields and matter. The recent (alleged) discovery of gravitational waves [5] was the result of observation of effects of such waves on the cosmic background radiation, and moreover, gravitational waves are certainly emitted by causal interactions.

Weaver maintains therefore that causation enters sound physical science by way of a proper understanding of general cosmological theories such as GTR. After all, spacetime points, according to GTR, are associated with “domains of influence” that are almost universally interpreted causally.

Crucially, GTR does not reduce the above causal influence talk to anything more fundamental or primitive, regardless of mistaken (according to Weaver) identification by some authors of causal influence structure with light cone structure [6].

Finally, as it is customary structure in many philosophy talks, the author considered (and attempted to rebut) a number of possible objections to his thesis.

The first such objection notes that the dynamical laws of GTR are time reversal invariant, which means that any causal reading of those equations implies a denial that causes necessarily precede their effects.

Here Weaver surprised me by simply shrugging the objection away! The principle that causes must precede their effects, he maintained is false. What he was referring to was the possibility of simultaneity of cause and effect, which has been proposed by others. The problem is that this would require a radical principle of instantaneous action at a distance, of the kind that Newton was worried about, as Weaver himself was keenly aware. The best he had to offer was the claim that instantaneous action at a distance may not actually be the case, but that the mere possibility is not incoherent. Okay then, but I thought we were talking physics, not logic.

Worse, the point about the time reversal invariance of GTR equations would also imply backwards causation, which Weaver accepts (well, he has to!) on the grounds that GTR does not preclude closed timelike curves [7], which in turn would make time travel possible [8].

Weaver also nodded toward the problem with quantum mechanics that I raised above, but said, and I quote: “well, you know, quantum gravity is a mess…”

A second objection points out that GTR is not itself a fundamental physical theory, so the causal reductionist should not be worried, at the least not yet. GTR will eventually have to yield to quantum mechanics in ways that would rub out any attempt to understand the causal activity of the gravitational field as fundamental physical activity.

To this Weaver, rather astoundingly, simply bit the bullet and acknowledged that okay, so maybe fundamental physics can do away with causality, but not all physical theories can. But this is worse than a Pyrrhic victory, I think. To begin with, because it is well established in philosophy of science that “special sciences” (i.e., everything but fundamental physics, including non-fundamental physics) do effectively deploy causal talk and cannot, apparently, do without it [9]. The puzzle of causal vs non-causal talk in science has always been at the fundamental level. If it turns out that the only reason GTR has to engage in causal talk is because it isn’t a fundamental theory (and we know it isn’t!), and that once we move to more fundamental levels of description and explanation causal talk yields to nomological talk (i.e., talk in terms of laws of nature) then the game is up for the critic of causal reductionism. Boy would I love to hear about this from physicists and philosophers of physics!
_____

Massimo Pigliucci is a biologist and philosopher at the City University of New York. His main interests are in the philosophy of science and pseudoscience. He is the editor-in-chief of Scientia Salon, and his latest book (co-edited with Maarten Boudry) is Philosophy of Pseudoscience: Reconsidering the Demarcation Problem (Chicago Press).

[1] Principle of indifference, Wiki entry.

[2] See: The Metaphysics of Causation, by Jonathan Schaffer, Stanford Encyclopedia of Philosophy.

[3] Principle of relativity; General covariance; Equivalence principle.

[4] Spacetime and Geometry: An Introduction to General Relativity, by S. Carroll, Addison-Wesley, 2003.

[5] Gravitational wave discovery looks doubtful in new analysis, by Clara Moskowitz, Scientif American, 22 September 2014.

[6] Light cone, Wiki entry.

[7] Closed timelike curve, Wiki entry.

[8] Unwinding time, by S. Carroll, The Wall Street Journal, 17 December 2011.

[9] See, for instance: Every Thing Must Go: Metaphysics Naturalized, by J. Ladyman and D. Ross, Oxford University Press, 2007.

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55 thoughts on “APA 2014-2: Against causal reductionism

  1. Hi Massimo,

    Just a short question — regarding the statement

    “… it is well established in philosophy of science that “special sciences” … do effectively deploy causal talk and cannot, apparently, do without it [9].”

    Can you provide some other reference for this, shorter than [9] and hopefully accessible via the Internet (i.e. a link to some ready-to-read online text)?

    Apparently, I seem to be blisfully ignorant of the fact that special sciences “cannot do” without causality, and I seem unable to fully understand that statement. However, my curiosity does not go as far as investing time and money to read a book of 300+ pages. Is there anything shorter available?

    Happy New year, 🙂
    Marko

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  2. Cause, effect, and time are all mysteries at this point.

    It was simple enough when Lorentz and Poincaré introduced the notion on “local time”. Time was relative (Poincaré Relativity Principle, 1904): it depended upon one’s state of motion. In a local frame moving fast, time slows down (relative to the friend who did not get on that speedy rocket).

    Einstein then observed that if a local time was accelerated, it would also slow down. Einstein somehow hoped to extract from this “General Theory of Relativity” a cause for inertia, but he failed (and could only fail, as GTR is local, not global). He ended up with just a Theory of Gravitation (Fock), a better and much improved version of the one of 1700, true… But still GTR is articulated basically the same equation arising from Ismael Bullialdus (1645; then Huygens, Borelli, Hooke).

    Enter Quantum Physics: time is absolute (oops). Locally absolute over an extent. Why? Because each Quantum processes are logically and mathematically analyzed in a particular space, relative to said process, and GLOBALLY therein (here is the globality Einstein was desperately searching for, as he craved for inertia).

    That particular space relative to that particular process is not just two dimensional (as in the famed double slit experiment), it can be pretty much anything that can be depicted as a Hilbert space (consider Dirac Spinor space).

    In the past, before 1904, one could consider that if something A preceded something else B, in time, A could have “caused” B. However local time already messes up with that situation (consider closed time loops in GTR; see “Interstellar”, relativist Thorne, made discoveries while making the movie).

    Quantum Physics makes causation a worse consideration than ever. As it stands, the Quantum is Non-Local. No need to get into Spin and Bell, to figure that one out: the analysis in Quantum Hilbert space uses time only as a one parameter transformation group, it’s intrinsically Non-Local (hence the famed “Collapse of the Wave Packet).

    If a physicist changes a spin axis on Earth, does it do something to the second member of the entangled photon pair he sent to Beta Centauri? Instantaneously? Really? No one knows for sure (and I don’t believe the “instantaneous” part), but the present Quantum formalism (sort of) says it does.

    Paradoxically, all of this debate about cause and effect has become very practical. As real physics moves away from the multiverse derangement syndrome, it ponders using, as nature and biology, and evolution do, the Quantum.

    Indeed, even biology uses the Quantum to compute, and find best solutions (as was demonstrated in the case of the chlorophyll molecule; much more examples are on the way, including that will demonstrate how a type of Lamarckian evolution works).

    “What causes what” has stood in the way of making Quantum Computers. Physicists have been trying to get a handle on causation. One wants to isolate the process of computation, yet get it impacted by complicated inputs, and only these.

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  3. Hi Massimo,

    Chris and I have talked about this alot (I am his dissertation adviser). I think it is important to distinguish 3 claims: 1. the fact that causal relations don’t occur in the equations of proposed fundamental physical theories (e.g. Hamilton’s equations. Maxwell’s equations, Shroedinger’s equation, the Einstein field equations) establishes that causation is not a fundamental relation (or not a fundamental relation needed for scientific explanations). 2. the fact that causal relations don’t occur in proposed fundamental physical theories provides some reason to think that causation is not a fundamental relation 3. The proper interpretation of some fundamental equations (e.g. the EFEs) require causation to be a fundamental relation. Russell and perhaps Schaffer seem to claim 1. I think Chris is right to reject it. But 2 seems to me to be correct and Chris may think that as well since he attempts to rebut it by arguing for 3. My view (but he disagrees) is that the arguments of his you mentioned for 3 at most show that interpreting the EFEs involves reference to causation. This doesn’t show that causation is fundamental though it does put the ball back in the reductionist’s court to show how the EFEs can be laws without causation being fundamental. This would involve a discussion of the controversial issue of whether being lawful involves causation.

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  4. Nice article Massimo, and I think I agree with most or all of it. I’m a little surprised to find you supporting causal reductionism.

    My own view is that causation may reduce to nomological entailment, but it would nevertheless appear to be a vital concept from the point of view of agents within the universe who perceive time as having a particular direction. It’s not really something metaphysically fundamental, but an abstraction we really can’t do without.

    “Worse, the point about the time reversal invariance of GTR equations would also imply backwards causation, which Weaver accepts (well, he has to!) on the grounds that GTR does not preclude closed timelike curves [7], which in turn would make time travel possible [8].”

    Here I think Weaver gets something else wrong. The equations of GTR are indeed time-symmetric, implying that backwards causation is as reasonable a perspective as forwards causation, but this is not best addressed by alluding to closed timelike curves or time travel. I think this point may best be understood by an example. We can say the ball bounces against the ground at time t=0 because it has downwards velocity at time t=-1 (forwards causation), but it is just as legitimate to say that the ball bounces (or must have bounced) at time t=0 because it has upwards velocity at time t=1. Time reversal invariance does not imply time travel but it does mean we can take the state of the universe at a later time and play the laws of physics in reverse and find the state at an earlier time. From the perspective of an observer with a reversed arrow of time, the future would appear to cause the past just as to us the past appears to cause the future. Forwards or backwards, causation is an abstraction, all that is going on at a fundamental level is the evolution of the universe according to physical law.

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  5. Here is a brief proposal of an approach:

    Consider the reverse code engineering (RCE) of some aspect of reality (AOR) into some domain-specific language (DSL). Some examples of some (actual) DSLs for some AORs:
    biological DSLs: LBS [1], GReg [2] , …
    quantum DSLs: Quipper [3], QuaFL [4], …

    First define: What does it mean for a language to have causality? [5] Then the question of reduction becomes a matter of translation or compilation of one DSL to another.

    [1] A Language for Biochemical Systems
    * http://homepages.inf.ed.ac.uk/gdp/publications/Lang_Bio_Sys.pdf
    [2] GReg : a domain specific language for the modeling of genetic regulatory mechanisms
    *http://ceur-ws.org/Vol-724/paper3.pdf
    [3] The Quipper Language
    * http://www.mathstat.dal.ca/~selinger/quipper/
    [4] QuaFL: A Typed DSL for Quantum Programming
    * http://cs-people.bu.edu/lapets/resource/quafl-lang.pdf
    [5] Causality For Free! Parametricity Implies Causality for Functional Reactive Programs
    * http://ect.bell-labs.com/who/ajeffrey/papers/plpv13.pdf

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  6. SciSal, you have said
    before that fundamental physics has no use for causal talk, and yet it is shown to you that Einstein and the physics textbooks use causal language. Causality is indeed central to fundamental physics, and I defy you to show me some part of physics that does not use causality.

    You say that it is “well established in philosophy of science” that fundamental physics can do without causality. Maybe so, but I doubt that you can find one physics textbook anywhere that agrees.

    It is also false to say “the field equations of GTR do not explicitly include any causal talk”. Those equations are hyperbolic partial differential equations, and solutions are causally determined by the Cauchy data. The GTR equations are as explicitly causal as any equations in all of science.

    Maybe you are using some peculiar concept of causality. I do not see why P1 (no causation) would imply C (causal reductionism). I would say that all fundamental physics is based on causality, and that is the best basis for causal reductionism.

    No one has to accept all solutions to GTR equations, such as time-like curves and backwards causation. It has always been understood that these equations constrain reality, but that lots of solutions are likely to be unphysical for other reasons.

    I also disagree with your claim that “we know” that GTR is not a fundamental theory. It is as fundamental as anything in physics. Even the string theorists, who argue that string theory is the truly fundamental theory, take GTR as one of their premises.

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  7. Hi Massimo,

    Of course, there is a huge literature on the very concept of causation itself, but we’ll leave that for another day. [2])

    I can’t help thinking that one needs to clarify the concept of causation before (or simultaneous with) discussing these topics. Let’s consider P1:

    P1) Physical science only requires natural law and physical history (no causation)

    If one knows the Schroedinger equation, the wavefunction, and the local environment at time T, then one can calculate the state of the system at time T + 1. Is that sufficient to say that the state of the system at time T “causes” the state at time T + 1?

    It certainly does in the sense of “if something is different at time T then there would be consequent differences at time T + 1”, which is perhaps the fundamental concept of causation. (In contrast, the later state is not “caused” by anything whose state at the earlier time is irrelevant.)

    If the answer to my above question is “no”, and something more than that is required for “causation”, then what is it? If one is going to say that “causation disappears from sophisticated physics” then we need to be clear what is being eliminated. The fact that causation might look different at fundamental scales and be described differently is not the same as eliminating the concept.

    Worse, the point about the time reversal invariance of GTR equations would also imply backwards causation, which Weaver accepts (well, he has to!) …

    I think that “imply” is too strong there, and “are compatible with” would be better. The fact that some fundamental equations are invariant under time reversal is not the same as saying that there must be backwards causation. That would only be so if the physics were complete, and we know it isn’t. Afterall, we have no empirical evidence for backward causation (or arrows of time running backwards).

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  8. Physics has this platonic idea that the mathematical construct is more real than the physical reality from which it was abstracted. Hence the “fabric of spacetime” is considered the physical explanation for the computational effectiveness of GR and the Copenhagen Interpretation, that reality is fundamentally statistical, has been put forth as the most accepted explanation for the effectiveness of Quantum Theory.

    Doesn’t anyone remember Epicycles??? How the “clockwork” universe was assumed to be constructed of giant cosmic gearwheels, as the explanation for the mathematical effectiveness of this geometric construct???? So did they find all the ever more refined cycles to make it work, or was there some inconvenient underlaying factor being overlooked? How many people here really truly believe they will put together the right combination of strings and multiverses to explain this current mess? How many currently employed, professionally reputable physicists are there, willing to question anymore than the more extreme proposals? I would have to say none. For example, I’ve been trying to make the entirely basic argument that time is not a vector from past to future, but the process by which future becomes past. Unfortunately this undermines the premise of spacetime, as it makes time an effect of action, rather than its basis and as such is similar to temperature, rather than space. Effectively time is to temperature, what frequency is to amplitude. When anyone willing to even debate the idea has to face the basic logic of it and can’t just bury it in claims of higher authority, they drop the discussion and disappear.

    I could also point out that even a moving car doesn’t have an exact location, which makes it a wave, but won’t push my luck…

    So yes, there is fundamental causality, but it is due to energy exchange, not sequence. For example, yesterday doesn’t cause today, anymore than one rung on a ladder causes the next. The sun shining on a spinning planet creates this effect of days, for those of us at one point on it. The problem is that linear narrative is foundational to our rational thought process, but that too is an effect. Just as we still see the sun rising in the east and setting in the west, as we have from the dawn of existence, we now realize it is the earth spinning west to east, so too we shall always experience that sequence of events and construct causal narratives out of it, but the larger reality is this thermodynamic process of creation and dissolution, expansion and contraction, etc, creating these situations and us and our perception of them.

    Not that I expect anyone to take this seriously, as there is no paycheck involved.

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  9. @Marko, the paper “From Causation to Explanation and Back” by Nancy Cartwright is a very good and frequently referenced article summarizing (albeit with a particular point of view) the causation/explanation issue. It’s freely available from the London School of Economics website I believe, just google it. It doesn’t deal with the “general” metaphysics of causation as deeply, it’s mainly about causal explanations in science. As far as I’m concerned that’s a good thing, since I’m skeptical of the value of much “general metaphysics” work on causation.

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  10. Marko,

    “Can you provide some other reference for this, shorter than [9] and hopefully accessible via the Internet”

    Other than the paper by Cartwright mentioned by Christian, I’d say to check out the SEP article on the unity of science (http://plato.stanford.edu/entries/scientific-unity/), the oft-cited (here at SciSal) classic by Fodor on the special sciences (https://ethik.univie.ac.at/fileadmin/user_upload/inst_ethik_wiss_dialog/Fodor__J._1974._Special_sciences_in_Synhtese.pdf), this one by Hugh Price (http://prce.hu/w/preprints/bertinoro.pdf), this by Menzies and List (http://personal.lse.ac.uk/list/PDF-files/CausalAutonomy.pdf), this by Raatikainen (http://www.mv.helsinki.fi/home/praatika/Causation%20Exclusion%20and%20the%20Special%20Sciences.pdf) toget you started.

    “I seem unable to fully understand that statement”

    It simply means that explanation in the special sciences always invokes — or seeks to invoke — causality. This is not the case, or rarely so, in fundamental physics.

    Barry,

    thanks for chiming in!

    “This would involve a discussion of the controversial issue of whether being lawful involves causation.”

    Indeed it would. If you or Chris are open to the possibility of writing an accessible essay on that topic at Scientia Salon, let me know, this is what this webzine is for.

    Disagreeable,

    “I’m a little surprised to find you supporting causal reductionism.”

    Well, let’s not get carried away. First, the term as used in the talk I wrote about has a much more limited meaning, I think, than what you usually refer to. Second, I actually do not think that causes are fundamental, though as Barry has pointed out, that would require a discussion of the issue of whether being lawful involves causation.

    “agents within the universe who perceive time as having a particular direction”

    On that one I’m with Lee Smolin: time *does* have a particular direction, regardless of the time-symmetry of equations in fundamental physics. It is something to be explained, not be treated as yet another “illusion.”

    “Time reversal invariance does not imply time travel but it does mean we can take the state of the universe at a later time and play the laws of physics in reverse and find the state at an earlier time”

    I hear you, but I’m not convinced, for the reasons that Chris alluded to in his presentation.

    “Forwards or backwards, causation is an abstraction, all that is going on at a fundamental level is the evolution of the universe according to physical law”

    Maybe, but that’s very much under debate, at the moment!

    schlafly,

    “yet it is shown to you that Einstein and the physics textbooks use causal language. Causality is indeed central to fundamental physics, and I defy you to show me some part of physics that does not use causality.”

    Quantum mechanics, for one. Or string theory. And just because Einstein used causal language this doesn’t mean the *equations* are somehow causal. As even Chris agreed, one has to make a distinction between the formalism and its interpretation. The formalism isn’t causal, it is (some of) its interpretations that are.

    “It is also false to say “the field equations of GTR do not explicitly include any causal talk”. Those equations are hyperbolic partial differential equations, and solutions are causally determined by the Cauchy data”

    You are again confusing the formalism with the interpretation of it.

    “Maybe you are using some peculiar concept of causality.”

    I’m not, and neither was Chris, as far as I can tell. Of course, how exactly to define causality is a whole other Pandora’s box…

    “It has always been understood that these equations constrain reality, but that lots of solutions are likely to be unphysical for other reasons.”

    Ah yes, but one needs a principled way to enforce such constraints, no?

    “I also disagree with your claim that “we know” that GTR is not a fundamental theory. It is as fundamental as anything in physics.”

    No, it isn’t. And neither is quantum mechanics. As long as there is going to be a more fundamental theory (and we know there has to be one) nothing above it is fundamental, pretty much by definition.

    Coel,

    “I can’t help thinking that one needs to clarify the concept of causation before (or simultaneous with) discussing these topics.”

    Not necessarily. As much as I’m fascinated by the literature on causation, it is pretty common, both in philosophy and in science, to deploy a concept without agreeing on a formal definition. Take the idea of genes in biology: it is far from straightforward to define what a gene is, and there are arguably multiple, only partially mutually compatible concepts floating in the literature. Still, if I say that my lab has been searching for genes affecting behavior X in animal Y I think we can proceed to discuss my research sidestepping the definitional issue, at the least most of the times.

    “It certainly does in the sense of “if something is different at time T then there would be consequent differences at time T + 1”, which is perhaps the fundamental concept of causation.”

    I’m not so sure. Consider that we are instead looking at the evolution of a mathematical equation, i.e., something that has no physical counterpart. I could write exactly what you wrote, then plot the evolution of the system of equations on a graph. Would you say that the position of the points on the graph is *caused* by the system of equations? I wouldn’t.

    “If the answer to my above question is “no”, and something more than that is required for “causation”, then what is it? If one is going to say that “causation disappears from sophisticated physics” then we need to be clear what is being eliminated.”

    Agreed, and I don’t have an answer. Currently the most interesting concept of causation I have encountered is the idea that causal interactions involve the exchange of physically conserved quantities (momentum, energy, etc.). But even that is actually debatable, so…

    “I think that “imply” is too strong there, and “are compatible with” would be better. The fact that some fundamental equations are invariant under time reversal is not the same as saying that there must be backwards causation. That would only be so if the physics were complete, and we know it isn’t.”

    That was Chris’ language, not mine, and I take your point. But if the physics is incomplete (and it is), then we are still left with the conclusion that even if we agree that GTR implies causal talk, that doesn’t establish that causal talk cannot be eliminated at a more fundamental level.

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  11. SciSal, you say that there is no causality in fundamental physics, but then you say that none of the known theories are fundamental. So your statement is vacuous.

    As Coel explained, quantum mechanics is causal. So is string theory. Both formally and in interpretation. The details are in any textbook.

    I looked at your references, and only Raatikainen addresses it most directly:

    … that there is genuine causation only at the fundamental micro-physical level. It would be important to note, though, that this is emphatically not how numerous distinguished philosophers of physics and experts in the theory of causation view the issue. …

    Now, in what follows, I do not want to commit myself to the view that there is no causation in fundamental physics – I do not even want to pretend that I am competent to judge the issue. However, it is important to keep in mind that many able philosophers have concluded this. But be that as it may, it just is not the case – contrary to what numerous physicalistic metaphysicians take for granted – that causation is uncontroversially present in fundamental physics. Therefore, such philosophers should perhaps think twice before declaring, from the armchair, that there is causation only at the fundamental physical level.

    He is saying that people who understand physics say that causation is uncontroversially present in fundamental physics. Philosophers say the opposite. He does not understand physics, so he is not judging.

    He also says:

    To begin with, it is a historical fact that the notion of cause has disappeared from physics as the subject has developed (see Kuhn 1971; cf. Loewer 2001). More importantly, many philosophers who apparently know their physics have argued that the whole idea of causation is not even applicable to fundamental physics, or is incompatible with it. Very briefly, and roughly, one of the problems is that in some cases, one has to specify the entire state of the whole universe at one time in order to determine the state of even a small region at some later time. And in such a case, it is difficult indeed to consider anything as a cause (Latham 1987, Redhead 1990, Field 2003, cf. Loewer 2001, Hitchcock 2007, Elga 2007; this idea goes back, of course, to Russell 1912-13).

    Yes, Russel said this, as I pointed out before. But this is crazy stuff. Almost every word of that paragraph is false. In particular, it is not true that “one has to specify the entire state of the whole universe at one time”. It is akin to astrology to believe that things are affected by the distant universe. The physics textbooks say that this is impossible. I assure you that Nobel prizes would be given to anyone who could show that the entire state of the universe was needed to determine the state of a small region.

    This is another example of how modern philosophy has diverged from science. Every single reference is over a century out of date in its understanding of science. This opinion of causality was foolish when Russell said it in 1913, and it is more foolish today.

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  12. Hi Massimo,

    I know you’re not endorsing reductionism as a whole. I think I understand causal reductionism, and I’m still a little surprised (though perhaps pleased) that you (tentatively) endorse it.

    I’ll agree that time has a certain direction in this place and time, and that direction is pointing away from the Big Bang (a moment of maximally low entropy) and towards the distant future (a moment of maximally great entropy). But I wouldn’t take it as a given that this direction is universal, especially if it is the case that the arrow of time always points from low entropy to high entropy.

    If there was a time before the Big Bang (which is under debate) then perhaps then the arrow of time would point in the opposite direction, still away from the Big Bang but now pointing towards our past. You can think of it as a kind of “temporal antipodeanism”.

    Similarly, if there is a time of very low entropy in the future (perhaps after thermal death of the universe, and an unbelievably long amount of time has passed such a thing may come to pass via random fluctuation), the direction of the arrow of time might reverse again.

    There may also be local regions of low entropy where the arrow of time could appear to be reversed. I think it unlikely that such regions would be large enough or long-lived enough to develop observers who would perceive this, but at small scales this certainly happens. To us it would look just like an improbable event taking place, like a proton and an anti-proton heading straight for each other from light years apart only to annihilate… an event which is more likely to happen in reverse (a proton and anti-proton spontaneously forming and speeding apart). The arrow of time is just the direction where these kinds of incredible coincidences are less common, but incredible flukes can and do happen whichever way you interpret the direction if you look hard enough and for long enough.

    I think I agree with Coel that for this particular topic it would be helpful to define what is intended by the term “causation”. We’re not just deploying the term in a day to day sense here, we are discussing its fundamental nature. Any such discussion would seem to be futile if not everybody is talking about the same thing. I think that this is why Coel and Schafly are disagreeing with you — it seems to me that they take issue with you because they see that causation is indeed present in physics, but the kind of causation they are talking about seems to me to be simply nomological entailment of the kind you allude to with your example of the points and the graph.

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  13. General Relativity is a bad case to discuss causation. First the whole theory is disturbingly close to a vast tautology. Einstein himself did not like the concept of “spacetime” (Minkowsky’s creation identifying space and time, and outrageously claiming that they were “interchangeable”, something basic Quantum Physics does not do… Although Quantum Field Theorists are prone to it, modulo the little detail of identifying time, with imaginary time…).

    Very long ago, I gave a talk at Stanford where I pointed out that Black Hole existence theory had Quantum loopholes (this has been recognized by the high authorities in attendance. Since. Hence the various controversies about the event horizon and the like).

    Equations are just abstracted talk. The abstraction makes computation manageable (perhaps the main interest of mathematics!). Thus it’s important to talk well. Perhaps the most important talk founding modern physics and mathematics had just one equation. See:
    Quantum Trumps Spacetime:
    https://patriceayme.wordpress.com/2013/08/08/quantum-trumps-spacetime/

    Massimo is right to say that the definition of the pudding is in the eating. The concept of “Gene” is an excellent example. It’s a work in progress. All of mathematics is made of castles up in the air, and it works very well, even with foundations reminiscent of the floating rock sky islands in “Avatar”.

    What’s causality? An event A is said to cause an event B if whenever A occurs, so does B. Thus one needs a definition of A, B, and of the implication itself. All come from statistic ensembles. Does that mean all causality arise directly from statistics? Not really: a differential equation E predicts (if well behaved!) the evolution of a system S. Then knowing S(t) one can get S(t+1). In this case one says that the initial conditions S(t) plus the law E cause S(t+1).

    Whether the equation E is time reversible, or not, is irrelevant: one plugs in (t+1), not (t-1).

    Differential equations or, more generally, evolution equations are all over physics. Those who say something as strange as “causation has disappeared from physics” should come up, with just one example of physics without an evolution equation. It will not be found, as physics is about predicting the future. (Better than predicting the past as all too many do.) (I agree with Coel & Disagreable.)

    The greatest quandary of modern physics is whether the Quantum Interaction (“Entanglement”) is causal. Thus the nature of causality is at the edge of science and technology at this point.

    (Sorry if that statement hurt the delicate sensitivity of multiversists and other multipolar disorder patients, and patient they have to learn to be, see how their Big Bang proof turned to dust last year…)

    Time has probably to do with Quantum Entanglement (my pet theory). That would be ineluctable if the Quantum Interaction occurs at finite speed (present Quantum Physics says it happens at infinite speed, thus violating causality). That would also make the whole universe irreversible. That seems more judicious to me, than to make time imaginary (as too many computations in Quantum Field Theory do).

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  14. Is this Chrisopher G Weaver? If so then I think I sniff an unstated agenda.

    In any case I would be interested in hearing the argument in his own words. I have disagreed with much he has said in the past (if it is indeed the same Weaver) but he is someone who does know a lot about how to put an argument together.

    Also, I would be surprised if he doesn’t have a very specific and technical definition of “cause”.

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  15. schlafly,

    I really wish you could engage in discussion without your customary open disdain for philosophy. One does wonder, given your attitude, what on earth you are doing on a site devoted to philosophy and maintained by a philosopher. Oh well.

    “there is no causality in fundamental physics, but then you say that none of the known theories are fundamental. So your statement is vacuous.”

    Let me try a different take: there are degrees of fundamentality, where, for instance quantum mechanics is more fundamental than relativity, and string theory (if true) would be more fundamental than QM. The point is that the further “down” one goes the less there seems to be need for talk of causality.

    “quantum mechanics is causal. So is string theory. Both formally and in interpretation”

    Yes, you keep repeating that, and I keep repeating my disagreement. At the very least I don’t understand how a formalism (i.e., a set of equations) can be causal. It’s math, not physics. It becomes physics only once it is given a particular interpretation. Beyond that, QM for instance describes the probabilities of certain events without invoking talk of causes. When we predict the spontaneous decay of an atom or particle, for instance, we just say that it happens with probability X, we don’t say “and it is caused by Y.”

    “This is another example of how modern philosophy has diverged from science. Every single reference is over a century out of date in its understanding of science.”

    That, my friend, is sheer nonsense on stilts.

    Disagreeable,

    “I know you’re not endorsing reductionism as a whole. I think I understand causal reductionism, and I’m still a little surprised (though perhaps pleased) that you (tentatively) endorse it.”

    Let me clear here: I am actually agnostic about whether causes are fundamental or not. By best understanding is that they are not. I am also agnostic about the nature of physical laws, though I am tempted by the more unorthodox views, like Smolin’s in physics and Cartwright’s in philosophy.

    “But I wouldn’t take it as a given that this direction is universal, especially if it is the case that the arrow of time always points from low entropy to high entropy.”

    Do you have any positive reason to think it isn’t?

    “If there was a time before the Big Bang … if there is a time of very low entropy in the future”

    As you know, both of these scenarios are highly speculative, to say the least. Why don’t we stick to the present universe, which is hard enough to understand?

    “I think I agree with Coel that for this particular topic it would be helpful to define what is intended by the term “causation”. We’re not just deploying the term in a day to day sense here, we are discussing its fundamental nature”

    Sure, so how about — only for the sake of argument — taking the concept I mentioned above, which is widely debated (and certainly not agreed upon) in the philosophical literature: causal events involve exchanges of physically conserved quantities. Does that help? (Not a rhetorical question, I’m genuinely curious.)

    “the kind of causation they are talking about seems to me to be simply nomological entailment of the kind you allude to with your example of the points and the graph.”

    That’s right, and no, I don’t count nomological entailment as causation. Indeed, that was a large part of the point in the essay.

    Robin,

    “Is this Chrisopher G Weaver? If so then I think I sniff an unstated agenda.”

    I believe it is, but I’m not sure what agenda you are referring to.

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  16. Hi Massimo,

    Consider that we are instead looking at the evolution of a mathematical equation, i.e., something that has no physical counterpart. I could write exactly what you wrote, then plot the evolution of the system of equations on a graph. Would you say that the position of the points on the graph is *caused* by the system of equations? I wouldn’t.

    No, I wouldn’t either. But then the equations there are only one part of the system, which also involves the mathematician.

    From the stance of scientific realism (pretty much the default of physicists), I’d regard the equations of physics as *descriptions* of a really-existing reality. Thus, using Schrodinger’s equation and knowledge of the state at time T we can calculate the state at time T + 1. We are then presuming that there is a reality whose state at time T “causes” the state at time T+1. In that sense causality is implicit in fundamental physics such as quantum mechanics. If we ask “why is that state at T+1 like it is?”, our answer would involve “because the state at time T caused it”.

    The fact that causality is implicit is apparent from: (1) the *lack* of *full* causality, where, for example, occurrence of radioactive decay at T+1 cannot be fully calculated (only probabilistically calculated) from the state at T. Also: (2) discussion of “non-local causality” in QM, where information from some distance away at time T is needed to calculate the state at T+1.

    Thus causality seems to be implicit in QM. We’re presuming that fundamental entities (whatever they are, strings or particles or wavefunctions or whatever) have the capability to cause the succeeding state. (Indeed, this capacity of “physically existing” entities to be causes seems to me to be what distinguishes physical entities from mathematical not-existing entities, which is why I don’t go along with Tegmark.)

    I’m still not clear why some are saying that QM doesn’t involve causation. Is it because QM is not formulated using the notion of a “force”, which dominated classical physics? Re-writing concepts of “force” in terms of more fundamental notions (quantum field theory) isn’t the same as dispensing with causation entirely. What attribute necessary for “causation” is suggested to be missing from QM?

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  17. This might be of interest (“causality” in the context of declarative vs. imperative programming):

    Models, or mathematical representations, of physical systems may be implemented in computer code that is declarative. The code contains a number of equations, not imperative assignments, that describe (“declare”) the behavioral relationships. When a model is expressed in this formalism, a computer is able to perform algebraic manipulations to best formulate the solution algorithm. The mathematical causality is typically imposed at the boundaries of the physical system, while the behavioral description of the system itself is declarative or acausal.
    http://en.wikipedia.org/wiki/Declarative_programming#Modeling

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  18. It’s interesting that Chris Weaver doesn’t characterize the early, very low entropy universe as unusual. As I see it, that early state is what allows us to measure the time since the Big Bang. Also, the steady increase in entropy provides a direction for time – allowing the past to appear set in stone while the future appears open to manipulation. Given enough time – and entropy increase – there will be no clocks, no way of determining past from future – and no one to even ask the question.

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  19. (As Coel pointed out). Old fashion causality involves forces. A force points from a point to another point (it’s called a “vector”; forces actually gave the mathematical concept of vector).

    However, there are no points in Quantum Physics.

    That there are points in Quantum Field Theory is a problem: string theory tried to get around it. That was perhaps its main motivation.

    In truth, Quantum Physics is all about Non-Commutative Geometry (and not just in Alain Connes’ restricted sense; this is the main argument for Super Symmetry).

    In Quantum Physics, there are waves. Quantum guidance is all about waves. According to De Broglie’s Wave Principle, all and any particle is guided by a wave. Yes, that would be true even for trucks. It was recently confirmed at a larger scale than atoms and molecules.

    Hitting a wave with another wave is messy. Causal, but messy. Thus causality in Quantum Physics tends to be probabilistic.

    Models of De Broglie’s Pilot Wave theory have recently appeared in labs (starting in Paris, where De Broglie’s ideas long pursued a subterranean existence; after all, De Broglie, who lived to nearly 100, was Perpetual Secretary of the Academie des Sciences). Even in the good old USA, these ideas are gaining traction:
    http://www.wired.com/2014/06/the-new-quantum-reality/

    The wave guiding proceeds at a speed much higher than the speed of light (at least 10^10 c). Call it TAU. Thus any Quantum Process embraces the totality of accessible space. Moreover that space is a Hilbert space (not just 3 dimensional space).

    This means that the causality (the set of causes) in any Quantum process involves not just a Cauchy data set, the classical way, and an evolution equation (Schrodinger, Dirac, Klein-Gordon, etc., but an entire space “visualized” by the Pilot Wave at speed TAU (> 10^10).

    Notice that many of the preceding is not part of the conceptology of those who claim that Quantum Physics is not causal. Most of them probably do not know what a Hilbert space is (that the Pilot Wave proceeds in a Hilbert was an early objection against it; it’s as intelligent as protesting that the sky is blue).

    Once all the ingredients are in, Quantum Physics is completely causal. Conceptually speaking.
    Those who are elaborating, as we speak, Quantum Computers are trying to make Quantum Physics so incredibly causal, that it will be able to easily make CAUSAL relationships that traditional classical computers cannot do (and cannot check!). One has to understand that classical computers work, indeed, according to classical mechanics. They are glorified water clocks (with electrons flowing).

    The Quantum Computer will convince the Commons that Quantum Physics is more causal than pathetically precise classical physics. Ultra pathetic precision lead classical physics to arbitrarily large errors. Whereas computing with waves is forgiving, hence more precise in the long run.

    Time to get causal in the wavy way, people, embracing wholeness and the implicate (spatial) order David Bohm was speaking (more or less) about. The real truth is going to be even more subtle.

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  20. Math is abstraction, not reverse engineering. It gives us a notational map of the territory, not the processes by which it came to be. It describes, not explains. Causality is a consequence of energy, not form, because energy is dynamic and conserved, while form is static and transient. That’s why consciousness moves toward the future, as thoughts move toward the past.
    Since biology evolved the central nervous system to process form/information, while the digestive, respiratory and circulatory systems process energy, there is a strong intellectual bias toward form, over energy.
    An example of how we rationalize form over even logic, would be to point to one of the initial patches to the Big Bang cosmology; When it was realized that all those distant galaxies appeared to be moving directly away from us, such that we would be the center of this expansion, it was decided that this was due to a relativistic expansion of space, based on the premise of spacetime and all points would appear as the center. The glaring flaw is that in order to be relativistic, the speed of light would have to increase, in order to remain constant to this dimension, but that would negate the Doppler effect working, since the light would be ‘energized.’ The Doppler effect requires motion in a larger frame to work, since the frequency is being stretched from the initial measure. In other words, there are more units, not stretched units between the initial points and so the light will take longer to cross the distance.
    This means that based on the redshift of intergalactic light, the vacuum of space is stretched, yet we measure this compared to the speed of the very same intergalactic light, across another, necessarily stable vacuum of space.
    If an accountant tried this sort of math, it would attract unwanted legal attention, but for cosmologists, the math says what they want it to say.
    Now an optical effect would quite easily explain why we would appear at the center, but that would step on too many toes of too many important people.
    Remember galaxies are not inert points, but according to Einstein, gravity wells. Basically the measure of space expanding between galaxies is balanced by the measure of space collapsing into them. Physically, mass contracts and radiation expands and there is a giant cosmic convection cycle and that redshift is simply evidence of Einstein’s original cosmological constant, proposed to balance the effect of gravity and as such, would be as integral to radiation as gravity is too mass, neither of which is fully explained.
    We accept gravity as “equivalent” to acceleration, yet the surface of this planet doesn’t accelerate in all directions to keep us stuck to it. So why wouldn’t redshift be “equivalent” to recession, without having those galaxies actually rushing away.
    The fact this rate increases with distance doesn’t mean dark energy, it just means the effect compounds and goes parabolic.
    Sorry to interrupt. Now go back to the storyline.

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  21. Hi Massimo,

    Regarding the arrow of time, it’s just that I find the argument that it pertains to entropy to be convincing, and that would seem to imply it need not always point in the same direction. Sean Carroll has made the point convincingly. It may be speculation, but asserting that the arrow of time is universally pointing in one direction only and that this is fundamentally built in is also speculation. Agnosticism would seem to be appropriate.

    Regarding the claim that “causal events involve exchanges of physically conserved quantities,” I don’t really find it particularly helpful, because I don’t understand how that is supposed to explain what causality is. It seems to be more an observation about the kinds of interactions that seem to happen. This is presumably further developed elsewhere so this is just my gut reaction rather than a considered judgment. It just doesn’t seem to be much of a definition.

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  22. Just a note on “abstraction, not reverse engineering”: Abstraction is a part of reverse engineering.

    Reverse engineering is defined* as “The process of analyzing a subject system with two goals in mind:
    1. to identify the system’s components and their interrelationships; and,
    2. to create representations of the system in another form or at a higher level of abstraction.”
    * http://www.program-transformation.org/Transform/ReverseEngineering

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  23. Hi SciSal,

    Not necessarily. As much as I’m fascinated by the literature on causation, it is pretty common, both in philosophy and in science, to deploy a concept without agreeing on a formal definition.

    Certainly most debates are conducted with incomplete definitions, but I would suggest that, in this case, the lack of a definition has caused you and Chris Weaver to be talking at cross purposes.

    For example you say that Christopher claims that the principle – that causes must precede their effects – is false, whereas he clarifies that he means that the principle that causes temporally precede their effects is false.

    It seems to make a big difference whether the cause effect relationship is supposed to describe a temporal and ontological precedence or just ontological precedence.

    To me, this indicates that the distinction between “There is a causal interaction between X and Y” and “X and Y are lawfully related” is ambiguous at best, calling into question whether “causal reductionism” has any clear meaning in the first place.

    Even in ordinary language the cause/effect relationship does not necessarily imply temporal precedence. For example if I have a weight tied to a string I can say that the weight causes the string to hang straight even if I had held the string straight prior to attaching the weight. Similarly I can say that the string causes the weight to stay in that position, even if it had been held in that position by some other means prior to attaching the string.

    So I would like to see, at least, sufficient definition of “cause” in order to distinguish between “X causes Y” and “X and Y are lawfully related”, otherwise I can’t see that there is really any difference of opinion here.

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  24. Hi DM,

    We can say the ball bounces against the ground at time t=0 because it has downwards velocity at time t=-1 (forwards causation), but it is just as legitimate to say that the ball bounces (or must have bounced) at time t=0 because it has upwards velocity at time t=1. Time reversal invariance does not imply time travel but it does mean we can take the state of the universe at a later time and play the laws of physics in reverse and find the state at an earlier time. From the perspective of an observer with a reversed arrow of time, the future would appear to cause the past just as to us the past appears to cause the future. Forwards or backwards, causation is an abstraction, all that is going on at a fundamental level is the evolution of the universe according to physical law.

    Sounds wrong to me. Say I am observing a ball heading towards the ground with a certain trajectory and velocity. Is there some way of telling from that information whether the ball was thrown by the boy standing on the ground some distance from me or pushed horizontally by the man in balloon above me? It seems that both of these scenarios could account for the ball’s current trajectory and velocity.

    The other way I look at this is to suppose I wake up tomorrow morning and find an envelope on my mantlepiece which contains a detailed description of all that I will do on that day (signed, say, God, The Doctor or Marty McFly).

    It seems to me that if I had such a document I could say to myself “let’s see about that” and do something other than was on the paper. But if this document really did come from my fixed future of my timeline then I should find it impossible to do otherwise. The document will say that I will pour myself a bowl of cornflakes and if I try to make myself a bowl of porridge instead I will find myself compelled to pour that bowl of cornflakes.

    Apart from that being counter intuitive, I would also wonder about what physics is stopping me from acting on the information I have.

    So it seems to me that whereas any amount of information about my past might be available to me without causing a paradox, the same does not go for information about my future. So I don’t think the situation can be symmetric.

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  25. Philip,
    That may well be, but it isn’t the entirety of the process.
    Consider; 1+1=2 is an abstraction, but 2-1=1 isn’t reverse engineering. It’s just another abstraction.
    Does the equation 1+1=2 exist as some form of platonic ideal, irrespective of any reality?
    In the void there would be no objects to add and addition is a verb, not a noun, so there would be no processing either. Now math says anything multiplied by 0=0. So in the void, there is no 1, because there is only 0, so how could there be some platonic mathematical formulation, without a physical process to enact it, of which the equation is an abstraction? So basically wouldn’t that reverse engineer the entire equation out of existence, if there is no physical reality to abstract it from in the first place?
    Now epicycles being a clockwork universe, the “fabric of spacetime” and the Copenhagen Interpretation are all based on the proposition that the mathematical formula is a physically real ideal and reality simply reflects it. That is description posing as explanation.
    Also points, lines and planes are described as having a zero dimension. Doesn’t the principle of anything multiplied by 0=0 apply to a point, as it would apply to an apple? An infinite number of dimensionless points don’t add up to a line, if they all have zero dimension. How about a point of zero dimension on the time vector; basically it would be a shutter speed of 0. How much light does that let in?
    Don’t get me wrong. Math is a very useful tool, but like all tools, it can hurt you, if you misuse it. It provides a static description, but that doesn’t negate the fact that reality is fundamentally dynamic. As I pointed out above, even a moving car doesn’t have an exact location and that blur of its motion is effectively a wave, in terms of position.
    When the ancient Egyptians were developing astronomy and astrology, they were two sides of the same coin; The description of the cosmic order and its explanation. One became geometry and the other became religion.
    We are surrounded by order, but we need to be very careful how we chose to explain it.

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  26. I’d just like to point out that Schlafly paraphrases me completely wrong: According to him, I say: “He is saying that people who understand physics say that causation is uncontroversially present in fundamental physics.”
    Quite the opposite! I wrote:
    “it just is *not* the case … that causation is uncontroversially present in fundamental physics.”
    and:
    ” many philosophers who apparently know their physics have argued that the whole idea of causation is not even applicable to fundamental physics, or is incompatible with it.”

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  27. Hi Robin,

    So you observe a ball falling. Is it going to hit the ground or is it going to be caught by the person standing near it, or is it going to be caught by a gust of wind and land in the pool?

    Just as in your example where the past is uncertain based on evidence observable in the present, the same is obviously true of the future. You can’t easily tell the future from the present without having all the information, and the same is true from telling the past from the present.

    In your example, you can of course tell if the ball was dropped from the balloon or thrown by the boy. You just need to have all the information. The brain state of the guy in the balloon and the brain state of the boy will record which one of them is responsible. If they somehow have amnesia, then the various velocities of all the particles in the vicinity will bear an imprint such that if you knew all this in detail to infinite precision you could in principle play it back.

    Nobody said this was easy (or even feasible), but predicting the future is hardly any easier.

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  28. Hi SciSal,

    I believe it is, but I’m not sure what agenda you are referring to.

    I suppose “agenda” is the wrong word. I only meant that with Christopher Weaver’s interest in Cosmological style arguments it must be important to establish causality as real and fundamental.

    The concept has long come under attack – Hume’s doubt that the concept is even coherent, or Berkley’s radical reduction of causes to signifiers.

    Of course this does not invalidate his points in any way.

    Hi DM,

    Let us say that it was machines that might have shot the ball from the ground or balloon. The machines are not necessarily going to record the fact that they shot the ball and if nothing has counted the number of balls that they had to begin with, then the information needed to reconstruct the past could disappear completely. If you have systems where different processes can map onto the same states then you have a non-reversible system.

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  29. I’m not sure that I get the issue, here.

    If the point is just that our ordinary language use of ’cause’ in the sense of — something “makes” something else happen — cannot be given a more rigorous or precise sense, then that is obviously true and we’ve known it since Hume.

    But if the point is that our most recent atomic physics reaches up, through layers and layers of description, and undermines the ordinary language use of “cause” then I’d like to hear an argument, and I haven’t heard one yet. Specifically, I’d like to hear what is wrong with the following sentence:

    “My punching John in the face caused his nose to break.”

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  30. Aravis,
    If I may use this as an example, consider these different expressions;
    “The energy transferred by my fist caused John’s nose to break.”
    Versus; The event of my hitting John’s nose preceded it being broken.
    Now if you quantify events, then there is a defined distinction between the preceding and succeeding, but if they remain connected by the flow of energy, then it becomes more difficult to make distinctions. So the conceptual process of distinction necessarily leads one away from causation.
    The reason quanta are statistically indeterminate is because that background from which they rise, is a bunch of other quanta.

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  31. Excellent article and a very important issue. I think that there are some conception confusions here.

    “Worse, the point about the time reversal invariance of GTR equations would also imply backwards causation, …”

    The time symmetry of a physics equation is only about its immutability, nothing about the reverse-arrow-of- time or backwards causation. That is, the equation which is discovered today worked zillion years ago too.

    “Weaver thinks that causal reductionism is based on an unsound argument from physics. …, where natural laws themselves are not “causal…. GTR does not reduce the above causal influence talk to anything more fundamental or primitive, …”

    GTR (general theory of relativity) is not fundamental; so it is not a good example here. But the idea that anything ‘Fundamental’ is not having further cause is a nonscientific idea ‘thus far’ (as never be discussed in scientific terms).

    First, the Aristotle causation (ACE) is not ‘universal’ but useful in a very small domain. A genuine cause does not always produce an ‘effect’. The Buddhism causation law (BCE) is a better one which adds the ‘boundary conditions’ as a key part of the law of causation. The same ‘cause’ with different boundary conditions can produce totally different ‘Effects’. One simple example is,
    A * B = C (such as, white and house = white house)
    A * B = D (white And house = Whitehouse)

    The and/And show the same causal but different boundary conditions.

    Second, this universe is built up in tiers vertically and in branches horizontally, and this building mechanism is ‘Similarity Transformation’, which is not exactly equal to either ACE or BCE. The higher tier is obviously ‘sitting’ on top of the lower ones, but there is not exactly the ‘causation’ relations between those tiers, at least not in the ACE or BCE sense.

    So, using the ‘causality’ to describe the structure of this universe is wrong, using the wrong tool.

    And, using the ‘reduction’ to describe the frameworks of this universe is wrong. Not only the higher tier can often not be reduced to the lower tiers in the ACE or BCE sense, but the side branches of this universe can definitely not be reduced to each other.

    However, if we use ‘causality’ in a wider sense (not in the ACE nor BCE), we might be able to say that the higher tier is caused by the lower ones. But, the key issue here is about the ‘Final Cause (base)’. 1) Is there a Final Cause? 2) If there is, does it have a deeper base?

    My answer is a big Yes for the first question.
    The second question is No.

    In order to discuss these two questions, I have wrote an article as preamble (see http://tienzengong.wordpress.com/2014/12/27/the-certainty-principle/ ) which is also a good example of this ‘causality’ issue.

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  32. Brodix: You are not answering the question that I asked. How does anything to do with quanta, reach up about a half-dozen levels of description and render problematic my sample sentence?

    Unless you are going to suggest that quantum mechanics shows that there aren’t “really” any fists or noses, my sample sentence stands un-contradicted and un-problematic. And if one *does* go that way, then we are back to the reductionism argument again, and I am not inclined to re-rehearse all the reasons why the “there are no fists, only quanta” line is a no-go. The last time I tried, the usual suspects just stuck their fingers in their ears and went “I can’t hear you!”

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  33. I think that the argument is that if the laws of physics are explaining why “punching John in the face caused his nose to break”, then we do not need causality anymore. That is, it is not really causality once it is understood. This reminds me of the philosophers who say that artificial intelligence (like playing chess) is not really intelligence once it becomes a cheap app on your smart phone.

    QM for instance describes the probabilities of certain events without invoking talk of causes. When we predict the spontaneous decay of an atom or particle, for instance, we just say that it happens with probability X, we don’t say “and it is caused by Y.”

    That was true a century ago. Physicists could measure the half-life of a radioactive element, and thereby say that the atom decays with probability X, but beyond that, spontaneous events were mysterious. Then quantum mechanics was discovered as a way to find causal explanations. Physical states are described by a wave function, time evolution is governed by a differential equation, and probabilities of (apparently spontaneous) events are given by a Hilbert space operators.

    Quantum mechanics is routinely applied to explain and predict chemical reactions, silicon chips, lasers, and much of modern technology. The explanations are completely causal, or you would not be able to read this message. While it might seem that your computer is spontaneously sending a signal, every component is designed with a causal understanding of how a state at one time is causing a state at a nanosecond later.

    I would go further, and say that incorporating causality into fundamental physics was the most important intellectual achievement in modern times. Before 1850, we did not have causal explanations for any of the four fundamental forces. Now we have fully causal theories for all four, and those theories have led to the most striking technological progress in the history of the planet.

    Panu, I appreciate your clarification, but it does appear that all the physicists believe that causation is present in fundamental physics, and all the philosophers believe the opposite. This is a funny controversy, because it does not appear that any philosophers actually talk to any physicists. If they did, then no one would say “it is a historical fact that the notion of cause has disappeared from physics as the subject has developed”.

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  34. Hi Massimo,

    Sure, so how about — only for the sake of argument — taking the concept I mentioned above, which is widely debated (and certainly not agreed upon) in the philosophical literature: causal events involve exchanges of physically conserved quantities.

    If we take that definition then General Relativity is causal. That’s because, if we take (for example) two stars and compute them orbiting each other using nothing but GR, then there is exchange of those physically conserved quantities.

    As for Quantum Mechanics, if we just take the pure evolution of an entangled wavefunction, then maybe there is no “exchange”, since that question isn’t being asked. But, QM is pretty useless and incomplete without some account of the wavefunction decohereing or collapsing (or one of the other more esoteric variants), and if you add that in then you do get exchange of those physically conserved quantities. Thus QM would be causal also.

    On the definition more generally, I would agree the reverse, that any interaction involving such exchange is causal, but I’m not sure why one would define causation that way. Causation seems to be a more fundamental concept than that, and I’d probably want to invoke it even when no such exchange is occurring. For example, if a lone particle is propagating in free space, I’d still want to say that the succeeding state of that particle is caused by the preceding state (I can’t think of any other reason for the succeeding state) — but that’s just my intuitive conception of “causation”, so I’m open to persuasion if anyone has a better and more rigorous one.

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  35. schlafly,

    “This is a funny controversy, because it does not appear that any philosophers actually talk to any physicists.”

    This is funny because it is so patently false. But sure, keep repeating yourself that, if it makes you feel better.

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  36. This below might be of interest regarding causation in the context of physics:

    Symposium on Mathias Frisch’s “Causal Reasoning in Physics”*
    February 6, 2015
    In philosophy of science, scientific methodology, and metaphysics, much has been written on the role of causal notions and causal reasoning in the so-called ‘special sciences’ and in common sense contexts. However, the most recent debate on causation focuses on whether causal reasoning also plays a role in physics. The majority view is that causation plays no role in physics (e.g. influentially articulated in Russell 1913, Price and Corry 2007). In his forthcoming book “Causal Reasoning in Physics” (Cambridge University Press), Mathias Frisch opposes this received view. …
    * http://www.mcmp.philosophie.uni-muenchen.de/events/workshops/container/symposium_frisch/index.html

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  37. Aravis,
    I’m not questioning your point. I’m just using it as a jumping off point to argue this distinction between the microcosmic level and ours, is more a problem of intellectual constructs, than actual physics. As I pointed out in other posts, information is necessarily static and that trying to describe a fundamentally dynamic reality in terms of static concepts creates these discontinuities. For example, even a moving car does not have a precise location, so effectively describing its location at a moment in time would amount to a wave, because there is no such thing as a zero dimension point, even in theory. It is simply a convenience.
    The quanta coming together as a fist, instead of traveling as a point particle, would be the energy of the wave being absorbed at a point. Much as a lightning bolt strikes the ground at a point.

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  38. Let me suggest what I think is going on here.

    Take at first a completely simple theory of electromagnetism, which of course allows for the existence of EM waves. Now imagine that there are at least two such waves heading towards one another in spacetime. At some point they interfere and create a complex pattern. Now consider two ways of analysing this.

    On the first view, the waves -caused- this pattern to exist.

    On the second view, what happened was that the EM field was evolving locally based on Maxwell’s equations. Consider one of the spacetime points where the complex interference pattern “lives”. I don’t think it’s right to say the value of the electromagnetic field at that point was -caused- by either of the two waves. It was at most “caused” jointly by the laws of electromagnetism and the state of the EM field in the preceding moment. But as (I think) Coel discussed above, that is in fact hardly worthy of being called “causation”.

    So we have two divergent accounts of the exact same physics. Note that what happened in the second case was that we looked, in detail, at the microscopic goings on, whereas in the first case we augmented our description of the situation by identifying two macroscopically perspicuous “objects” – the waves. And that’s what we do all the time in physics – we work with the laws, but also group fundamental entities or their structures together into manageable “chunks” which are easier to model and/or describe in words. Such “chunks” are of course the emergent entities of all the various special sciences and it often makes sense to invoke causal talk when discussing them.

    And I think that if you look at all the alleged cases of causality in GR and/or QM, you’ll see this exact thing pulled off time and time again. Gravitational waves cause stuff? Waves are emergent objects, or structures in the underlying gravitational field. Gravity affects objects? Well, yes – those objects are emergent entities and it may well make sense to use causal talk when they’re concerned. Neither of those cases shows that the fundamental, underlying physics employs causal talk in the slightest.

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  39. Massimo,

    Thanks for the references! They are on my todo list. 🙂

    Also, regarding your tentative definition of causality,

    “causal events involve exchanges of physically conserved quantities”

    it appears to me to be an interesting idea. However, I would be reluctant to accept it universally, due to the following corner-case issue: it is fairly uncontroversial to say that the redshift of light coming from distant galaxies is *caused* by the expansion of the Universe. Yet the photons in question do not exchange energy with anything. Moreover, generally speaking, energy is not even a conserved quantity (especially in a cosmological context). So there seem to be some aspects of causality that are not properly covered by that definition. Of course, I am aware that you have already labeled the definition as highly debatable, so consider this just as a technical remark. 🙂

    Schlafly,

    “Then quantum mechanics was discovered as a way to find causal explanations. Physical states are described by a wave function, time evolution is governed by a differential equation, and probabilities of (apparently spontaneous) events are given by a Hilbert space operators.”

    I beg to differ. The very fact that we talk about probabilities means that events are *really* spontaneous, as opposed to “apparently spontaneous”. QM does not provide causal explanations, and I believe that Massimo has got the physics right.

    “…it does appear that all the physicists believe that causation is present in fundamental physics, and all the philosophers believe the opposite.”

    I beg to differ again. I am a physicist, and not only that I do not believe that causation is present in fundamental physics, but moreover I have a hard time understanding what “causality” even means in the context being discussed here. Note that I asked for additional references so that I could try to understand it better, and hopefully “translate” the concept of causality to anything even remotely meaningful in the language of fundamental physics. The only (partial) success I had so far is to understand causality as a convenient high-level language for describing evolution of physical systems that are approximately deterministic. Nothing more than that (so far, I am yet to finish reading those references).

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  40. Marko,

    “The only (partial) success I had so far is to understand causality as a convenient high-level language for describing evolution of physical systems that are approximately deterministic.”

    Thanks, that’s – I think – pretty much the way it is understood by a number of philosophers of science. As for the conserved quantities issue, I’m not endorsing that view, and yes there are at the least apparent counterexamples like the one you mentioned. I just think it’s at the least an interesting starting point for further discussion.

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  41. Mathias Frisch does indeed say, “According to a view widely held among philosophers of science, the notion of cause has no legitimate role to play in mature theories of physics.” He is not too interested in the opinions of physicists except to note that a popular modern textbook says that the principle of causality is “the most sacred tenet in all of physics”. Elsewhere I found a philosophy book that said that physicists adhere to “causal fundamentalism, which claims that the job of all of physics is to uncover the prevalent causal relations in nature.” So yes, there is a severe split between philosophers and physicists on this issue.

    Dominik, in EM theory the fields at some spacetime point are caused by the fields and waves in the backwards light cone from that point, as per Maxwell’s equations. And yes, that has commonly been called causation for 150 years.

    You seem to be saying that causality in GR is not fundamental because gravity waves are emergent. However there is not any (relevant) distinction between fields and waves in GR. Not in EM either. The Sun causes the Earth to stay with a gravity field. You can think of it as the Sun sending gravity waves to the Earth, altho the ripples in the waves are not detectable. If you admit that the waves are causal, then you have to admit that the fundamental field is causal.

    Marko, all of the sciences talk about probabilities, so that talk does not make anything “really spontaneous”. And whether or not it is really spontaneous does not have anything to do with causality. Something can be caused whether spontaneous or not. Maybe there are philosophers of science who think that causality is restricted to deterministic systems, but not physicists.

    You say that redshifts are caused, but that QM does not provide causal explanations. If you are really a physicist, then you surely know that those redshifts are displacements of spectral lines that are entirely explained by QM. So what are you trying to say, that there is no causal explanation for the lines, but there is one for the shifts in the lines? You will not find anything like that in a physics textbook.

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  42. Dominik, Marko, Massimo,
    This goes to the dichotomy of energy and form. Waves are an expression of form and as such are part of the pattern, but they are a transmission of energy. For a slightly different example, consider a rock being thrown at and breaking a window. Now if you gently held the rock against the window, it wouldn’t break. So it is not the contact of the rock to the window, but the energy transmitted by the rock into the window.
    As for redshift, it is very much caused by the loss of energy, or at least the dispersal over a larger/increasing area, relative to the reception from the emission.
    As for universal energy, there is no claim it is being actually lost, but rather dispersed over increasing space. Entropy only applies to “working energy in a closed system.” That is because it tends toward thermal equilibrium, not that it no longer exists.
    In an infinite system, energy radiated from one area would be balanced by energy being radiated away form adjoining systems.
    Quanta popping into and out of existence do so from the background energy, it is just that they can only be predicted, since the form of this energy cannot be measured. That is the issue, as we only can detect what we can measure and that is the form this energy takes.
    So the issue is whether it is actually space expanding, or the energy. As it is mass contracting and so that measure is said to shrink.

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  43. I think I am mostly with Aravis on this one. And, though I’m not a scientist, so hesitate saying this, I’m not convinced that the use of causal language in some scientific explanations really means that the sciences are bound to a metaphysical principle of causation to get their jobs done. For instance, it would seem that the mathematics used in physics is used to describe relationships and events, “caused” would be an interjection from common language to explain these, but not a necessary one. But again, I may be misunderstanding the matter.

    However, that said, along with Aravis, I think that the common language usage of the notion of causality is useful shorthand and won’t go away. (It also has important rhetorical value, especially in the courts, as when John’s lawyer has to argue why whoever broke John’s nose ought to pay the hospital bill.)

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  44. Schlafly,

    “all of the sciences talk about probabilities, so that talk does not make anything “really spontaneous”.”

    Most sciences employ probability to account for our level of ignorance about a system. But in QM the probability is a fundamental property of nature, independent of our ignorance. That’s why I said *really* spontaneous — in QM being spontaneous (i.e. without a cause) is a *real* property of the system itself, not a property of our knowledge (or ignorance) about the system.

    “Something can be caused whether spontaneous or not.”

    I understand the word “spontaneous” to be equivalent to “not being induced by a cause”. This is common in physics, for example when discussing spontaneous vs. stimulated emmision of photons.

    “You say that redshifts are caused, but that QM does not provide causal explanations. If you are really a physicist, then you surely know that those redshifts are displacements of spectral lines that are entirely explained by QM.”

    The frequencies of the spectral lines are explained by QM. But the actual process of a photon being emitted from an atom can be fundamentally probabilistic (this is called spontaneous emission, as opposed to the stimulated emission — the former is causeless, the latter has a cause). Maybe you should brush up your physics a bit, for example start here: http://en.wikipedia.org/wiki/Einstein_coefficients#Einstein_coefficients.

    “So what are you trying to say, that there is no causal explanation for the lines, but there is one for the shifts in the lines?”

    Roughly speaking, yes. More precisely, (1) there is no causal explanation for the emission of lines, (2) there is causal explanation for their frequencies, and (3) there is causal explanation for the redshift. (1) is causeless due to fundamentally probabilistic nature of QM, (2) is causal because QM upholds conservation of energy (almost deterministically), and (3) is causal because GR is a deterministic theory (and despite nonconservation of energy).

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  45. Schlafly,

    You write that
    “in EM theory the fields at some spacetime point are caused by the fields and waves in the backwards light cone from that point, as per Maxwell’s equations. And yes, that has commonly been called causation for 150 years.”

    And while it may be correct that physicists have at time called this causation, they must have been wrong, as EM is manifestly time-reversible. So there can be no microscopic matter of fact whether event A has caused event B or event B has caused event A.

    As to the second issue, you miss my point, which is that causality only starts making sense when we consider emergent objects. A gravitational wave is an emergent object of sufficient complexity “living” in the field (and not strictly identical to the field) – therefore it can enter causal relations. I don’t believe you engaged with that conception.

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  46. Hi Dominik,

    And while it may be correct that physicists have at time called this causation, they must have been wrong, as EM is manifestly time-reversible. So there can be no microscopic matter of fact whether event A has caused event B or event B has caused event A.

    Can you expound on why you think the second sentence follows from the first? To make a comparison, the basic equations of general relativity and cosmology are also time reversible, and therefore are equally compatible with a contracting universe heading towards a Big Bang.

    Yet the observations show clearly that there is a fact of the matter as to which is occurring — we are in an expanding universe, not a contracting one (and not both, either!) (and this is nothing to do with thermodynamics and a second-law “arrow”).

    Thus, pointing to time symmetry in fundamental equations doesn’t seem to me to be sufficient to say that we cannot distinguish between the two directions.

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  47. Coel, I’m curious about Dominik’s answer, but there is another way to bite that bullet: to say that the formalism of GR is not, in fact, causal, and one needs something additional to make it so. Like the brute observation that time actually happens to move in one direction. To be clear, it seems to me a non negotiable part of whatever definition of causality that there is an asymmetry between cause and effect. Otherwise we may be thinking of something else…

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  48. Brodix wrote:

    For example, even a moving car does not have a precise location, so effectively describing its location at a moment in time would amount to a wave, because there is no such thing as a zero dimension point, even in theory. It is simply a convenience.

    —————-

    Funny, this morning my moving car definitely had a location. It started out in my garage, drove down the street to my daughter’s best friend’s house, and then returned after picking up said daughter.

    If I had committed some driving infraction and a policeman pulled me over, he’d write the “precise” location at which he caught me, in his report. A relativistic or quantum mechanical defense that I was not at that precise location would not get me out of a ticket and would likely irritate the judge.

    I don’t find any conception of “precision” beyond this one interesting or useful for 99.99999% of the reasons why we are interested in identifying the locations of things like cars.

    Put another way, while these issues are fascinating at the level of fundamental physics, they tell us exactly nothing about the concept of causality as it operates in the world that we experience and inhabit.

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  49. Coel,

    To make a comparison, the basic equations of general relativity and cosmology are also time reversible, and therefore are equally compatible with a contracting universe heading towards a Big Bang.

    Yet the observations show clearly that there is a fact of the matter as to which is occurring — we are in an expanding universe, not a contracting one (and not both, either!) (and this is nothing to do with thermodynamics and a second-law “arrow”).

    As you said yourself, it is *observations* which tell us that the universe is expanding rather than contracting. The theory itself (GR) does not tell you that. The theory gives us two solutions of equations of motion, the expanding and the contracting solution — and we pick one over the other by imposing a boundary condition, which breaks time-symmetry. This boundary condition is not a part of the theory, but rather a reflection of the observation you speak about, and is imposed onto the theory “by hand”.

    So I’d say that Dominik is right — the theory itself does not distinguish between cause and effect, we put this distinction into the theory from the outside, i.e. from observation.

    Thus, pointing to time symmetry in fundamental equations doesn’t seem to me to be sufficient to say that we cannot distinguish between the two directions.

    The theory (be it GR or EM) doesn’t distinguish the two time-directions. We do. And we do it (ultimately) by appealing to thermodynamic irreversibility. This situation is called the “arrow of time problem”, so far an unsolved one.

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