On the role of evolutionary explanations in psychology
Published: September 18, 2010Tags: evolution evopsych cogsci
The idea of applying an evolutionary perspective to the study of psychology has been hugely controversial, and I've never fully understood why. Dualistic theory of mind has been effectively dead for a very long time. Just about everybody who thinks about these things today is of the opinion that the structure and function of the mind is a reflection of the structure and function of the brain. The brain is made of cells, and so when it comes to scientific explanations of its structure and function, evolution is the only game in town. Any complete account of the human mind and how it came to be must necessarily include an evolutionary component.
These are all of the objections to integrating evolutionary thinking into psychology that I have either seen or can anticipate, and why none of them hold water:
- "Evolutionary psychology is bad because it will (or might) end up providing a scientific justification for racism, sexism, or some other unpleasant -ism". This is a straight up example of the well known is-ought fallacy. It's absolutely not a valid argument against EP or anything else.
- "Evolutionary psychology is a junk science full of speculative "just so" stories without any hard evidence". This may well be a valid criticism against some, or even many, of the particular ideas which have been developed under the guise of evolutionary psychology, but it's not a good reason to discard the entire field. The appropriate response to bad science which combines evolution and psychology is good science which combines evolution and psychology, not a declaration that evolution and psychology shall never meet. Such a declaration can only be justified by an argument that good evolutionary psychology is impossible in principle. As far as I know, no convincing argument of this kind has been made, and it seems unlikely to me that one ever will.
- "But, but, but, what about culture?". Bringing evolutionary thinking into psychology does not eliminate the possibility of cultural explanations for some phenomena, and in turn the explanatory power of culture does not completely eliminate the need for evolutionary thinking. Culture isn't magic: any given cultural influence on thought necessarily has to (i) be an influences on something, and that something has to have existed prior to the particular cultural influence under consideration, and (ii) have bene acquired by some mechanism, which again has to have existed prior to this particular cultural influence. Evolution is the only thing which can terminate the infinite regress which results from trying to use culture as an explanation for everything. Biological evolution and cultural evolution are complementary processes, and not at odds with one another.
- "Not everything in an organism's phenotype represents an adaptation to some function. The evolutionary process can also lead to traits which are exaptations, or spandrels". This is a prefectly valid claim in and of itself (although it's not necessarily true - I haven't done enough reading on the "Darwin Wars" to definitively come down on the side of Dawkins or Gould, although I'd love to have done so and fully intend to do so), but it doesn't really remove the role for evolution in psychology. It discredits one particular conception of evolutionary psychology, i.e. the conception in which everything is an adaptation. But all this does is force us to widen our conception of what evolutionary psychology is, from "explaining as much of psychology as possible in terms of adaptations" to "explaining as much of psychology as possible in terms of adaptations, exaptations or spandrels".
- "The mind is emergent magic! Chaos, fractals, self-organisation!". My characterisation of this school of thought is tongue-in-cheek, but it does represent a perfectly legitimate take on the human mind. However, once again, it's not a magic ticket away from evolution. The full complexity of the human mind may well emerge in some seemingly magical way from the simple, local interactions of individual neurons in the human brain, but that same complexity does not emerge from extremely similar simple, local interactions of individual neurons in the brains of cats and dogs. Clearly there is some set of preconditions for the emergence of various psychological traits, and if we establish what those preconditions are we will be faced with the task of explaining how evolution drove our brains to meet those preconditions from a previous state which did not. Evolution cannot have proceeded with foresight toward those preconditions because of the benefits that would emerge from them: each step along the way must have yielded its own benefits, and the story isn't complete until we know what those steps were and why they happened.