Human nature is a funny thing. Some scientists, like biologist E.O. Wilson  and linguist Steven Pinker  are pretty convinced it is a real thing, and that it seriously constrains what we are going to do with our lives (the entire discipline of evolutionary psychology, or sociobiology as it was known in its first incarnation, is predicated on it).
Then again, plenty of philosophers I have talked to in recent years seem to be genuinely surprised that one could still talk about such a thing in all seriousness . Surely that quaint idea went out the window after decades of criticism of genetic determinism, they say. This, of course, despite the fact that there is a long and venerable tradition in philosophy of perfectly comprehensible talk about human nature .
Indeed, even people like Pinker seem to be sending somewhat mixed messages about the whole concept: on the one hand he vehemently (and justly) attacks the idea of a “blank slate” (though I don’t actually know too many people who hold onto it in anything like the original, strong, Lockeian version ). On the other hand, however, he claims — huge data sets in hand — that human beings have been able to yield to the “better angels” of our nature and have progressively built societies characterized by less and less violence .
Because of my original training as an evolutionary biologist interested in nature-nurture issues , I guess I never understood the (alleged) dichotomy. My basic take is that human behavioral traits (“human nature”) are the result of a continuous and inextricable interaction between our genes and our environments — which means that it makes no sense to ask what percentage of what we do is “caused” by genes and what percentage by the environment. If you add the well established concept, in evolutionary biology, of phenotypic plasticity — the idea that different sets of genes help produce wider or narrower ranges of behaviors in response to the quality of environmental inputs, and that the majority of these environmental inputs are nowadays the result of cultural forces — you’ve got a fairly solid framework to argue that yes, there is such a thing as human nature, but no, it isn’t unchangeable.
You might think that this would reassure both the scientists who insists (rightly) that human beings are not infinitely malleable blank slates, and the humanists who are (again, rightly) weary of the sinister socio-political implications of strong biological determinism. Everybody wins, can we go home now?
No, unfortunately it ain’t that easy. Too many scientists doggedly insist in not taking their humanist critics seriously enough, and too many humanists equally stubbornly resist giving even an inch to anything that smells like “biogilization.” It is not by chance that C.P. Snow famously called this divide “the two cultures” .
But the debate in question is far from new, and perhaps it will help taking a closer look at one of its most interesting previous incarnations, dating back to the Enlightenment, and featuring some of the most prominent British empiricist philosophers, chiefly David Hume. I will summarize the debate as reconstructed in a lovely paper by Michael Gill published a number of years ago in Hume Studies . Gill bases his analysis on what Hume writes in the aptly titled, given our topic, Treatise of Human Nature , and sets it against the background of a controversy concerning the origins of human sociability then raging among Bernard Mandeville (who was actually Dutch), Francis Hutcheson, and Anthony Ashley Cooper, Third Earl of Shaftesbury [11, 12, 13]. Throughout the following, of course keep in mind that all of this was pre-Darwin and pre-Mendel. Nonetheless, at the end I will attempt to bring Hume’s ideas as they emerged from the debate with his contemporaries up to speed and we’ll see what sort of Humean modern view of human nature we may be left with.
Gill’s main thesis is that Hume developed a “progressive” account of human nature, against the backdrop of a discussion among three of the so-called “late philosophers” in England, the above mentioned Mandeville, Hutcheson and Shaftesbury. They all agreed that human beings are social, but disagreed on the origins of our sociability: for Mandeville (in classic Hobbesian fashion) it is self-interest; for Hutcheson and Shaftesbury it is natural benevolence.
Shaftesbury presented as evidence of our benevolent nature the fact that we derive so much pleasure from friendship and other social interactions, and even from the very fact of doing good deeds. Similarly, Hutcheson said that we have an innate sense of public good (we feel good when others are happy, cringe at others’ misery) and moral good (approve of virtue and disapprove of vice).
Mandeville was of a very different opinion, according to which our basic nature is selfish and we organized in groups only to protect ourselves, first from natural dangers, then increasingly from each other. Modern society’s complex “commerce” and “standards of politeness” are made possible by our ability to communicate and write, but are still rooted in our original selfish nature.
What about Hume? On the one hand, he was no egoist (in the Hobbesian sense), as he thought humans are endowed with natural virtues. On the other hand, he squarely said that justice is not natural, but rather the result of (cultural) “artifice.”
A major part of Hume’s argument is that justice is not common among pre-civilized humans, and it requires training. It cannot, therefore, be natural. (Yes, I know, modern readers rightly cringe at this sort of statement, but bear with me a little longer, we’ll get to how Hume has now been corrected and updated on this point by recent empirical research.)
To understand Hume’s further discussion we need to keep in mind that for him a virtue consists of having a certain motive for action. Now the motive for justice cannot be regard for justice, on pain of circularity. It can’t be self love either (although it did exist in pre-civilized humans, and is therefore natural, according to Hume), since this will often be in conflict with justice. Hume also rejected regard for public interest as a motive for justice, thus apparently (but only apparently!) landing squarely in Mandeville’s camp.
Indeed, Hume went so far as to conclude that “In general, it may be affirm’d, that there is no such passion in human minds, as the love of mankind, merely as such, independent of personal qualities, or services, or of relation to ourself.” Emotions about other human beings, maintained Hume, are always directed at particular individuals, not at humanity in general. The converse is true as well: we don’t get a sense of justice by generalizing our feelings for particular individuals, because sometimes we ought to and do behave justly toward people we deeply dislike.
Hume agreed with Mandeville (and with Hobbes) that we have developed societies because we would otherwise have a hard time surviving on our own. So, societies originated out of the self interest of individuals. The fact that justice then also arises from selfish motives can be derived from the observation that we simply wouldn’t need justice if we were naturally disposed to respect the interests of others.
Where Hume began to diverge from Mandeville is with the latter’s contention that, essentially, we are all hypocrites when we talk about morality. For Hume, rather, people have genuine moral feelings of justice. Hume’s middle way between Mandeville on one hand and Hutcheson and Shaftesbury on the other, is the idea that we initially want justice for selfish reasons, but eventually develop a mental association that leads us to approve of justice even when it runs counters to our selfish motives.
To recap the situation so far: Hume agreed with Mandeville that justice is an artificial virtue originating in self interest; but he also agreed with Hutcheson and Shaftesbury that people exhibit genuine non self interested feelings of justice. All three of his predecessors would have thought these two positions to be mutually incompatible.
One way to look at this is that the three in question adopted (different) static, “originalist,” views of human nature. Hume, by contrast, upheld a dynamic, progressive view, where originally selfish motives can develop into genuinely altruistic ones. 
The Humean engine for this change is the famous principle of association: we begin by disapproving of acts of injustice that do not affect us (because they tend to be harmful), and we end up conjoining disapproval and injustice in general. Which means we develop a broader disapproval of all unjust acts, including those that benefit us. This mechanism, says Hume, applies not just to justice, but to all morally relevant sentiments.
Gill makes a final interesting point by drawing a distinction between two senses in which one may ask about the “origins” of something: chronological and functional. For instance, we could ask what is the origin of the Constitutional powers of the American government and provide two very distinct, not mutually exclusive, answers: they came from a Constitutional convention held in Philadelphia in 1787; and they are rooted in consent of the people (at least in theory). The first answer is chronological, the second is functional.
Gill suggests that the three pre-Humeans simply assumed that chronological and functional explanations coincide in the case of moral sentiments, while Hume’s innovation consisted in decoupling them. Here is how Hume himself very clearly put it: “Thus self-interest is the original motive to the establishment of justice; but a sympathy with public interest is the source of the moral approbation which attends that virtue.”
What are we to make of the Humean solution to the Mandeville-Hutcheson-Shaftesbury debate, from our post-Darwinian and post-Mendelian perspective? Roughly speaking, we could say that both Mandeville, on one hand, and Hutcheson and Shaftesbury, on the other, were early versions of what today we would call biological determinists — they only disagreed on the qualitative nature of that determinism (selfish for Mandeville, benign for the other two). And of course I have already mentioned Locke’s “environmentalist” view, even though he was not directly involved in the tale recounted by Gill (and was increasingly disparaged by Hume, as the years went by).
Hume’s position, however, can be updated in a more nuanced and interesting way, from the vantage point of modern biology and social science. At the risk of stretching Hume’s own intention (but, really, I am interested in what to make of human nature, taking Hume only as an inspiring starting point), I am going to suggest that his acknowledgment of a “natural” status for our moral feelings is a due and reasonable concession to the “naturist” camp in the nature-nurture debate. There is no getting around it: human beings are a particular biological species, characterized by a historically inherited genetic environment that constrains the way we act, feel and think. What elevates this to the lofty status of “human nature” is that our closest evolutionary cousins (bonobos, chimpanzees, and other great apes) have a significantly different genetic and behavioral repertoire — despite of course a certain number of (expected, since we are talking about evolution) similarities.
But Hume’s principle of association can be profitably recast as an embryonic theory of cultural evolution, according to which we are capable of generating novel (genuine) feelings out of a combination of experiences and our ability to reflect on those experiences.
Even so, we need to acknowledge that Hume was at the least partly wrong on empirical grounds — a correction he would have very likely not objected to, given his interest in grounding “moral” philosophy (i.e., all philosophy outside of natural philosophy) in a better understanding of human nature. As it turns out, a mounting body of work shows that not only members of all human societies (“primitive” or not), but even other species of primates show clear signs of an innate sense of fairness, which is the grounding for our concept of justice .
Moreover, and this is far more problematic, we also need to admit that — despite much interest and a number of valiant efforts — we really don’t quite have a good theory of cultural evolution at hand. I tend to be somewhat skeptical of Darwinian-type theories of cultural evolution, for the chief reason that culture seems to be much more obviously a Lamarckian-type process. And I truly think nothing of so-called memetics, for a number of reasons that I will perhaps get into (again: ) at some future time (but mostly, because “memes” are a rather uninformative, if not downright misleading, metaphor and nothing else).
At any rate, the basic, somewhat Humean (or Hume-inspired) outline of what I’m thinking about is that human nature — i.e., what it is to be human, as opposed to, say, being chimpanzee — evolves both genetically and culturally, with the two constantly interacting with each other, and yet, I think, with the cultural component becoming more and more independent of the genetic one.
Consider, as a controversial example, Pinker’s own theory in The Better Angels of Our Nature, that violence has more or less steadily gone down throughout human history (yes, despite two world wars in the 20th century!) at the least in part because of our ability to talk to each other and originate and spread (philosophical) ideas about democracy, justice, and so on. If Pinker’s outline is even remotely close to the truth, then we have a situation where pre-existing feelings of intra-group fairness and cooperation, which we inherited from our primate ancestors, gradually, via cultural evolution, got more elaborated and became applied more broadly, generating what Peter Singer refers to as our enlarging circle of empathy and moral concern .
The idea is that if, indeed, we are making moral progress (as Singer suggests, and as Pinker-style data seem to confirm), then this in an important sense counts as a change in human nature, but it is one achieved largely via cultural evolution, itself grounded in our specific genetic heritage as social primates.
There is, of course, much more to be said to satisfactorily fill in the details of this sort of broad picture, but the picture itself is certainly one with which Hume would have been pleased.
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).
 E.O. Wilson, On Human Nature, Harvard University Press, 1978.
 S. Pinker, The Blank Slate: The Modern Denial of Human Nature, Viking, 2002.
 See, for instance, J.J. Prinz, Beyond Human Nature: How Culture and Experience Shape Our Lives, Norton, 2012.
 J.J. Kupperman, Theories of Human Nature, Hackett, 2010.
 See the Stanford Encyclopedia of Philosophy article on Locke.
 S. Pinker, The Better Angels of Our Nature: Why Violence Has Declined, Viking, 2001.
 M. Pigliucci, Phenotypic Plasticity: Beyond Nature and Nurture, Johns Hopkins University Press, 2001.
 C.P. Snow, The Two Cultures and a Second Look: An Expanded Version of the Two Cultures and the Scientific Revolution, Cambridge University Press, 1964.
 M. Gill, Hume’s progressive view of human nature, in Hume Studies 26:87-108, 2000.
 D. Hume, A Treatise of Human Nature, 1738 (Project Gutenberg version).
 Bernard Mandeville (15 November 1670 – 21 January 1733), was a Dutch philosopher, political economist and satirist. Born in Rotterdam, Netherlands, he lived most of his life in England and used English for most of his published works. He became famous for The Fable of the Bees.
 The Rev. Francis Hutcheson (8 August 1694 – 8 August 1746) was an Irish philosopher born in Ireland to a family of Scottish Presbyterians who became one of the founding fathers of the Scottish Enlightenment.
 Anthony Ashley Cooper, 3rd Earl of Shaftesbury (26 February 1671 – 4 February 1713) was an English politician, philosopher and writer.
 For a modern version of this, see E. Sober and D.S. Wilson, Unto Others: The Evolution and Psychology of Unselfish Behavior, Harvard University Press, 1999.
 See, among others: F. de Waal (et al.) Primates and Philosophers: How Morality Evolved, Princeton University Press, 2006.
 See: M. Pigliucci, Memes, selfish genes and Darwinian paranoia, Rationally Speaking, 26 July 2009; as well as: M. Pigliucci, Is cultural evolution a Darwinian process?, Rationally Speaking, 11 March 2013.
 P. Singer, The Expanding Circle: Ethics, Evolution, and Moral Progress, Princeton University Press, 2011.