One of the recurring themes at the February 4, 2014, debate between Bill Nye and Ken Ham  was Ham’s continuous harping on a supposed distinction between “observational science” (science we can observe in real time) and “historical science” (science that must be inferred from the past). I was part of the team that coached Bill Nye before the debate, and we told him to expect this over and over again. Sure enough, Ken Ham beat it to death. This strange distinction is one of the main talking points for Ham, although he clearly used it because it is widespread through the Young-Earth Creationist literature. For example, creationist Charles Thaxton  contrasts the supposedly reliable operations of (experimental) science with the “speculative” science of origins. The 2007 creationist textbook Explore Evolution distinguished “experimental science” from “historical science” . Geisler and Anderson  distinguish “empirical” or “operational” science from “forensic” or “origins” science. In their words:
It is the proposal of this book that a science which deals with origin events does not fall within the category of empirical science, which deals with observed regularities in the present. Rather, it is more like a forensic science, which concentrates on the unobserved singularities in the past. … A science about the past does not observe the past singularity but must depend on the principle of uniformity (analogy), as historical geology and archaeology do. That is, since these kinds of sciences deal with unobserved past events (whether regular or singular), those events can be “known” only in terms of like events in the present. … The great events of origin were singularities. The origin of the universe is not recurring. Nor is the origin of life, or the origin of major new forms of life. These are past singularities over which creationists and evolutionists debate. Evolutionists posit a secondary natural cause for them, creationists argue for a supernatural primary cause.
Many examples could be found in the older creationist literature, going back to the publications of Henry Morris, Duane Gish, and the “Acts & Facts” series of the Institute for Creation Research. Among currently active creationists, Ray Comfort uses it often as well , and I’ll bet it’s part of the curriculum in evangelical creationist schools like Liberty University, Oral Roberts University, Bryan College, and many others. In the debate, Ham kept pounding on it again and again, refusing to recognize any scientific evidence that couldn’t be witnessed in real time.
As many scientists  have pointed out, this distinction is bunk, and only Ken Ham and the Young-Earth Creationists seem to think that it makes any sense. Naturally, he repeats this phony artificial distinction because it serves his purposes. Each time Nye pressed him on one point or another, Ham retreated behind his dodge of no one can know anything of “historical” past, then made the stupefying assertion that the only reliable source of information about the past is the Bible. (Nye was too much of a gentleman to raise the obvious challenge ask Ken how he can possibly know this. As Ham always puts it, “Were you there?”). Most of science tells us that the earth is old, that life has evolved, and so on. Ham wants to discredit and throw all this information away, so he creates a convenient but untenable distinction that serves his purposes — but bears no relation to what real scientists do or think.
As P.Z. Myers commented  in his Pharyngula blog:
It’s got that delightful combination of arrogant pretense in which the Bible-walloper gets to pretend he understands science better than scientists, and simultaneously allows them to deny every scientific observation, ever. This is the argument where they declare what kinds of science there are, and evolutionary biologists are using the weak kind, historical science, while creationists are only using the strong kind, observational science. They use the distinction wrongly and without any understanding of how science works, and they inappropriately claim that they’re doing any kind of science at all.
In reality, all science is a seamless mix of things we observe directly, and things we infer using natural laws extended into the realms of the past, the very distant, or the very tiny (what is called “uniformitarianism” or “actualism”). As Myers puts it:
All scientific evidence is observational, but not in the naive sense that all that counts is what you see with your eyes. There is a sense in which some science is regarded as historical, but it’s not used in the way creationists do; it does not refer to science that describes events in the past.
Using Ham’s distinction, we could never say anything about the universe, because most objects are so far away from us that their light has traveled hundreds to thousands of light-years or more to reach us. What we see already happened long ago. Yet in the debate Ham conceded that many objects in space are thousands or more light-years away, an admission that he is recognizing “historical” science — apparently without realizing it. At one point, he even seemed to concede that some stars were more than 6000 light-years away, which contradicts his assertion that the earth is only 6000 years old — unless he wanted to fall back on Gosse’s strange Omphalos argument and claim that objects were made to look as if they had an ancient past. Instead he made this astounding statement :
When we hear the term light-year, we need to realize it is not a measure of time but a measure of distance, telling us how far away something is. Distant stars and galaxies might be millions of light-years away, but that doesn’t mean that it took millions of years for the light to get here, it just means it is really far away!
Apparently, Ham does not grasp the concept of light-years, which makes sense. Because he cannot admit that anything happened before 6000 years ago, he must construct strange, unfounded “explanations” for this uncomfortable reality. No matter how much he tries to rationalize the meaning of “light-year,” if something is millions of light-years away, then it really does take millions of years for its light to reach us. That’s how light-years are defined — the distance that light travels in a year. Ham here clearly displays his complete ignorance of real science.
In addition, if Ham were correct about the nature of science, we could not say much about things at the very tiniest scale of things: molecules, atoms, and subatomic particles. As anyone who has taken chemistry or physics knows, nearly all the properties of molecules or atoms were inferred years ago by indirect methods, using their chemical and physical behavior. No one could see molecules directly, much less atoms, when they were first discovered and described. (Only recently with the advent of scanning tunneling microscopes have we been able to image molecules and some atoms). So does Ham want to assert that chemistry and atomic physics are not real sciences because we can’t watch their objects of study in real time? If he does, how does he explain all the things we have learned and all the things we have invented using this knowledge?
When we coached Bill Nye for the debate, we knew this was coming, and gave Bill several examples to refute it. The best one is the television show “CSI” (an abbreviation for “Crime Scene Investigation”), which celebrates forensic science. If a crime is committed and no one saw the criminal, do the CSIs just shrug their shoulders and say “we can’t solve it”? Obviously, they don’t. The whole point of the show is that there are many clues all over the place that allow us to reliably infer things about the past, whether a few hours after a crime, or a few million years. Let’s say a burglar robbed Ham’s house while he was participating in the debate. Would he insist that the CSIs stop working the crime scene because he doesn’t believe in “historical science”? Not likely. Rather, he’d want them to use any science that would solve the crime — just like real scientists use any evidence available to solve the mysteries of nature.
Nye briefly mentioned CSI in his first segment. He indicated that Ham’s use of the phony distinction between historical and observational science was peculiar to creationism and completely false — but that did not stop Ham to going back to it again and again. Another angle that I suggested (though Nye did not use) was to bring up the predictive power of historical science. We study ancient earthquakes recorded in the sediments, and it allows us to predict future earthquakes. We study ancient volcanic deposits around active volcanoes like Mt. St. Helens or Mt. Rainier, and it allows us to predict their next eruption. In particular, Bill (the Planetary Society President), could have brought up the example of Halley’s comet. In 1705, Edmond Halley used Newton’s Laws and the historical record of comets going all the way back to 240BCE as well as famous appearances such as in 1066 (coinciding with the Norman conquest), 1456 (co-occurring with the fall of the Byzantine Empire), 1531, and 1607, to realize that all of these observations were of the same comet which passed by the earth every 75-76 years. Halley’s use of this historical data allowed him to predict the comet would return in 1758, which did occur. Sadly, Halley himself never saw it, because he died in 1742, but this is a classic example of how science is a seamless whole. From inferences about the past drawn from various historical records Halley made a successful prediction about the future. That is science at its best.
I was fortunate to see Halley’s comet in 1986 during its last pass by earth. Although it was not as impressive as it was in 1066 or 1758, it was worth the effort to view it, because I won’t live long enough to see it again when it returns in 2061. One of the interesting quirks of history is that Mark Twain was born the year it arrived in 1835, and died at age 75 when it appeared in 1910. As he famously said,
I came in with Halley’s comet in 1835. It is coming again next year, and I expect to go out with it. It will be the greatest disappointment of my life if I don’t go out with Halley’s comet. The Almighty has said, no doubt: ‘Now here are these two unaccountable freaks; they came in together, they must go out together.’
Sure enough, Twain died on April 21, 1910, the day after the comet appeared in the sky.
So where do the creationists get the idea that this alleged distinction between historical and observational disciplines is recognized in science? One example is used by Ken Ham and many other creationists, such as Gordon Wilson, who said the following :
I made it clear 9 years ago and this semester that I wasn’t going to promote my views or disparage evolutionary views in class. That said, I have stated that I do not share the views of common descent held by the main stream scientific community. Which is well within my rights to do. The only thing that I have presented (briefly) is a distinction between historical science and empirical science, and that conclusions drawn from the former don’t have the high level of certainty as conclusions drawn from the latter. This distinction is not a creationist invention. Ernst Mayr holds to this as well. The conclusions drawn from historical science are as good as the presuppositions on which they are based. This was simply a moment to encourage students to exercise some critical thinking skills in assessing truth claims of the scientific community.
He, and other creationists, quote Ernst Mayr (out of context) as follows :
Evolutionary biology, in contrast with physics and chemistry, is a historical science — the evolutionist attempts to explain events and processes that have already taken place. Laws and experiments are inappropriate techniques for the explication of such events and processes. Instead one constructs a historical narrative, consisting of a tentative reconstruction of the particular scenario that led to the events one is trying to explain.
For example, three different scenarios have been proposed for the sudden extinction of the dinosaurs at the end of the Cretaceous: a devastating epidemic; a catastrophic change of climate; and the impact of an asteroid, known as the Alvarez theory. The first two narratives were ultimately refuted by evidence incompatible with them. All the known facts, however, fit the Alvarez theory, which is now widely accepted. The testing of historical narratives implies that the wide gap between science and the humanities that so troubled physicist C. P. Snow is actually nonexistent — by virtue of its methodology and its acceptance of the time factor that makes change possible, evolutionary biology serves as a bridge.
However, if you read the entire context of the Mayr quote, in no way does he suggest that “historical science” is inferior or less reliable than “experimental” or “observational” science. That is a creationist distortion, designed to make what the scientists actually say sound like it supports their ideas. In many ways, it is analogous to the way creationists willfully misunderstand the meaning of the word “theory.” They act as if “theory” only meant a “wild, speculative scenario” (as in the popular usage), and do not acknowledge that to a scientist, a “theory” is a body of observations that is now well tested and supported. No matter how many times you correct them on this deliberate obfuscation, they will not abandon it because it fits their audience and their ideological agenda.
The contrast between more “observational” types of science and more “historical” science is indeed found in the literature of philosophy of science, but in no case do true philosophers of science argue that “historical” evidence is inferior or less trustworthy. Only creationists do that. Some philosophers and scientists have made the distinction popularized by Stephen Jay Gould , between the “nomothetic” (emphasizing the law-like, regular, predictable, experimental) aspects of science, and the “idiographic” (emphasizing unique, one-of-a-kind historical events). For example, Elliott Sober wrote :
This division between nomothetic (“nomos” is Greek for law) and historical sciences does not mean that each science is exclusively one or the other. The particle physicist might find that the collisions of interest often occur on the surface of the sun; if so, a detailed study of that particular object might help to infer the general law. Symmetrically, the astronomer interested in obtaining an accurate description of the star might use various laws to help make the inference.
Although the particle physicist and the astronomer may attend to both general laws and historical particulars, we can separate their two enterprises by distinguishing means from ends. The astronomer’s problem is a historical one because the goal is to infer the properties of a particular object; the astronomer uses laws only as a means. Particle physics, on the other hand, is a nomothetic discipline because the goal is to infer general laws; descriptions of particular objects are only relevant as a means.
The same division exists within evolutionary biology. When a systematist infers that human beings are more closely related to chimps than they are to gorillas, this phylogenetic proposition describes a family tree that connects three species. The proposition is logically of the same type as the proposition that says that Alice is more closely related to Berry than she is to Carl. … Reconstructing genealogical relationships is the goal of a historical science.
As is clear from this quote, and many others that could be found in the literature of philosophy of science, in no way is “historical” evidence considered inferior to “observational evidence.” They are a seamless continuum, with many kinds of problems using both evidence in parallel, or lines of evidence merging from one into another. Sober says so clearly, and I couldn’t conclude in a more clear fashion myself :
Although inferring laws and reconstructing history are distinct scientific goals, they often are fruitfully pursued together. Theoreticians hope their models are not vacuous; they want them to apply to the real world of living organisms. Likewise, naturalists who describe the present and past of particular species often do so with an eye to providing data that have a wider theoretical significance. Nomothetic and historical disciplines in evolutionary biology have much to learn from each other.
Donald Prothero is a paleontologist, geologist, and author who specializes in mammalian paleontology. His research has been in the field of magnetostratigraphy, a technique to date rock layers of the Cenozoic era and its use to date the climate changes which occurred 30-40 million years ago. He is the author or editor of more than 30 books and over 250 scientific papers, including five geology textbooks. His most recent book is Reality Check: How Science Deniers Threaten Our Future.
 The full debate is available online.
 Thaxton, C.B. (1984) The Mystery of Life’s Origins: Reassessing Current Theories. Allied Books, Ltd., London.
 Meyer, S., et al. (2007), Explore Evolution: Arguments for and against Neo-Darwinism. Hill House Publishers, New York.
 Geisler, Norman L. and J. Kerby Anderson (1987) Origin science: A proposal for the creation-evolution controversy. Grand Rapids, MI: Baker Book House, 198 pp.
 See Pharyngula, 27 July 2013.
 Pharyngula, op. cit.
 At Answers in Genesis.
 Nothing in Biology, 26 February 2014.
 Scientific American on Darwin’s influence.
 Gould, S.J. 1980. The promise of paleobiology as a nomothetic, evolutionary discipline. Paleobiology, 6: 96-118.
 Sober, E. (2000) Philosophy of Biology 2nd ed., Westview Press: Boulder, CO. pp. 14-15.
 Ibid., p. 18.