A strange thing is happening in modern philosophy: many philosophers don’t seem to believe that there is such a thing as human nature. What makes this strange is that, not only does the new attitude run counter to much of the history of philosophy, but – despite loud claims to the contrary – it also goes against the findings of modern science. This has serious consequences, ranging from the way in which we see ourselves and our place in the cosmos to what sort of philosophy of life we might adopt. Our aim here is to discuss the issue of human nature in light of contemporary biology, and then explore how the concept might impact everyday living.
The existence of something like a human nature that separates us from the rest of the animal world has often been implied, and sometimes explicitly stated, throughout the history of philosophy. Aristotle thought that the ‘proper function’ of human beings was to think rationally, from which he derived the idea that the highest life available to us is one of contemplation (ie, philosophising) – hardly unexpected from a philosopher. The Epicureans argued that it is a quintessential aspect of human nature that we are happier when we experience pleasure, and especially when we do not experience pain. Thomas Hobbes believed that we need a strong centralised government to keep us in line because our nature would otherwise lead us to live a life that he memorably characterised as ‘solitary, poor, nasty, brutish, and short’. Jean-Jacques Rousseau embedded the idea of a human nature in his conception of the ‘noble savage’. Confucius and Mencius thought that human nature is essentially good, while Hsün Tzu considered it essentially evil.
The keyword here is, of course, ‘essentially’. one of the obvious exceptions to this trend was John Locke, who described the human mind as a ‘tabula rasa’ (blank slate), but his take has been rejected by modern science. As one group of cognitive scientists describes it in From Mating to Mentality (2003), our mind is more like a colouring book, or a ‘graffiti-filled wall of a New York subway station’ than a blank slate.
In contrast, many contemporary philosophers, both of the so-called analytic and continental traditions, seem largely to have rejected the very idea of human nature. A prominent example is our colleague Jesse Prinz at the City University of New York, who argues forcefully for what is referred to as a ‘nurturist’ (as opposed to a ‘naturist’) position in his book Beyond Human Nature: How Culture and Experience Shape the Human Mind (2012). More recently, Ronnie de Sousa argued that modern science shows that human nature does not exist and, drawing on Jean-Paul Sartre’s notion of radical freedom, concluded that this favours an existentialist philosophical outlook. We beg to differ.
What exactly does science tell us about the idea of a human nature? If we take evolutionary biology seriously, then we certainly should reject any essentialist conception of it, such as Aristotle’s. There is no immutable, clearly defined ‘essence’ that characterises human beings, and only them, within the whole animal world. From Charles Darwin onward, the scientific consensus has been pretty clear: we are but one species among millions on Earth, members of a not particularly numerous branch of the tree of life, endowed with unusually large and structurally complex brains. Our particular lineage gave origin to the species Homo sapiens at least 300,000 years ago, resulting from a long evolutionary period, which unfolded over millions of years from the point of divergence from our most recent common ancestor with the chimpanzees, our closest phylogenetic cousins.
Put that way, it would seem that biology does indeed do away with any idea of human nature: whatever characteristics our species possesses are the result of a continuous process of evolutionary differentiation from other species of primates, and there is no reason to believe that such process is over, or will be any time soon. Moreover, people are fond of citing the famous figure that humans and chimpanzees differ ‘only’ in about 1-2 per cent of their genomic sequence, implying that we are not really as special as we’d like to think.
But as Kevin Laland has pointed out in his book Darwin’s Unfinished Symphony: How Culture Made the Human Mind (2017), that small percentage translates into thousands of structural changes at the genetic level, which in turn can be combined to yield millions of ways in which humans are distinct from chimpanzees. Just because the difference is small in percentage, it doesn’t mean it is not both very obvious and highly consequential.
In light of this, we think that the picture emerging from evolutionary and developmental biology is – contrary to the widespread opinion among contemporary philosophers – one that very much supports the notion of human nature, just not an essentialist one. Human nature is best conceived of as a cluster of homeostatic properties, ie of traits that are dynamically changing and yet sufficiently stable over evolutionary time to be statistically clearly recognisable. These properties include characteristics that are either unique to the human species, or so quantitatively distinct from anything similar found in other animals that our version is unquestionably and solely human.
Take language, for instance. Plenty of other animals (and even plants and bacteria) communicate, meaning that they exchange signals aimed at improving their own or their kin’s survival. But no other living species has anything even remotely like human language, with its complex grammar and high levels of recursion (where a linguistic rule can be applied to the results of the application of the very same rule, and so on). Other animals, such as octopuses, have large, complex brains and nervous systems, but no other animal has both the size (relative to the body) and especially the structural asymmetry and layering of the human brain; for instance, its enormously developed frontal cortex, which is in charge of reward, attention, short-term memory tasks, planning and motivation.
The list could go on and on, but the basic point is that it is fallacious to state that there are no fundamental differences between humans and other animals just because the boundaries are fuzzy and dynamic (over evolutionary time). As Justice Potter Stewart said, in a case about pornography versus art in 1964: ‘I shall not today attempt further to define the kinds of material I understand to be embraced within that shorthand description; and perhaps I could never succeed in intelligibly doing so. But I know it when I see it.’ A modern biologist and a scientifically informed philosopher could say something very much along the same lines about human nature. We all know it when we see it.
Now, if human nature is real, what are the consequences from a philosophical perspective? Why should a philosopher, or anyone interested in using philosophy as a guide to life, care about this otherwise technical debate? Let’s explore the point by way of a brief discussion of two philosophies that provide particularly strong defences of human nature and that are aligned with cognitive science: existentialism and Stoicism.