Friday, September 30, 2005

Some Thoughts on Evolutionary Theory in Philosophy

In the notes below, I am glossing and commenting on a text by Bence Nanay, "The Structure and Significance of Evolutionary Explanations in Philosophy."

Evolutionary theory has become the ur-explanatory theory in many branches of philosophy. In philosophy of mind, evolutionary explanations are used to explain the development and nature of mental content and consciousness; in ethics, they are used to explain altruism, care, and responsibility; in epistemology, they are used to explain the development of doxastic practices and justificatory schemes; in aesthetics and political philosophy, they are used to explain the development and dissemination of "memes." Evolutionary theory, it seems, can be used to explain almost anything. Regardless of the explanandum, the explicans remains evolutionary theory.

What is evolutionary theory, then, apart from its explanandum? That is, what is essential to all of these explanatory patterns independent of the content which they purport to explain? The essence of evolutionary explanation is selection. The selection process can most generally be defined as repeated cycles of replication involving interaction with an environment.

We can distinguish two types of selection processes, and we will need to decide whether each is appropriate for philosophical explananda. The first type is cumulative; the second is non-cumulative. We are familiar with cumulative selection processes from biology where the explanandum is the gene pool of an organism. As organisms with a favorable trait survive and reproduce while those without it do not, the successive replications cumulatively alter the genes in the direction of those with the favorable trait. Thus, the selection process is cumulative by offering adaptation-explanations. (Note: explanation shifts from the individual level at which the adaptation is relevant, to the population-level at which the selection process is operative. For some, this is a flaw in the argument, but it seems clear, protests the contrary notwithstanding, that selection processes can and do offer the best explanation for adaptations in individuals.)

Another way to put the point is that cumulative selection processes explain why an adaptation occurred by showing its purpose. Whether "purpose" is defined as real or a primary quality "in" the adaptation or as a heuristic tool, some notion of purpose is operative in explanations involving cumulative selection. (This is complex point that Banay sidesteps altogether.) The same may not be so easily said of questions like, why is there more oxygen in the Earth's atmosphere than in Mercury's? If selection processes were at work in those cases, it would be non-cumulative because, as far as we can say, there is no evidence of an adaptation involved in that outcome.

Thus, if philosophy aims to employ evolutionary explanations to explain why such things as mental content or altruism came to be and what they are for, it will need to invoke a cumulative (not a non-cumulative) selection process.

Another point to keep in mind is that evolutionary explanations in philosophy should not be reductive. For example, if the evolutionary explanation replaces the philosophical explanandum (e.g., consciousness or doxastic practice) with a non-philosophical explicans (physics or biology), then the explanation will cease to be philosophy and will be unsatisfactory as a philosophical explanation.

Let's consider some examples. First, evolutionary psychology. According to evolutionary psychology, our mental capacities have to be analyzed with reference to the environment in which they evolved. Such a claim is common for explanations of the evolution of eyes and hands, and so it should be relevant for mental capacities as well. For example, the preference for sugar is an adaptation to the environment of the Pleistocene era, and so it would be a mistake to view it as necessarily connected to our present environment. While this mental capacity does figure centrally into philosophical debate, evolutionary psychologists also deal with many capacities that do, e.g., consciousness itself, language, and ethics. One problem with this form of explanation is that the environment in which the adaptation is purported to have occurred cannot be known directly. Instead, it must be stipulated. Thus, evolutionary psychology uses stipulated selection processes as explicans in lieu of known selection processes. (Is the distinction between stipulated and known selection processes as stark as Banay suggests? There is surely more than mere stipulation involved here.)

Next, let's consider Richard Dawkins' meme theory. A "meme," according to Dawkins, is any unit of cultural transmission. Thus, a meme can be anything from a catchy tune or flashy style of dress to the ideas of democracy or God. Some memes survive in memory, while others fade to oblivion. Using an evolutionary model to explain culture and even political philosophy, Dawkins argues that memes function like genes by competing with one another for survival in the minds of the population rather than its gene pool. One difficulty with this analogy of meme and gene is that there is no counterpart to the alleles of genes in meme theory. That is, in sexual reproduction genes compete with their alleles--the rivals for the one chromosomal slot. Memes, however, do not have such a structure with predesignated slots and binary options for filling them. While there are some relations among memes, their selection process is not strictly cumulative. It is true that the fading from collective memory of memes relating to medieval life have cumulative effects on other memes, such as the memes for feudal authority relations (e.g., phrases like "my lord" or the supplicant posture of serfs) or the chivalric code or warfare practices and weapons. In other words, losing touch with some memes may make others likely to lose their sense (place with the linguistic system) and significance (capacity to refer to the world). Still, the point is that this becomes very murky and not at all universal. The notion of competing memes cannot be defined systematically because the relations among memes are not binary or direct. Thus, meme theory is an evolutionary theory that is non-cumulative, and for this reason it fails as explanation of adaptation because it cannot say how these memes came to survive while others did not. Since the competitors of memes are not well-defined, meme theory cannot claim to show what the memes are for such that the selection process would favor them over the competitors.

Next, evolutionary epistemology. According to evolutionary epistemology, all thinking is continuous replication with blind variation and selective retention. Environmental interactions with thoughts will survive amidst the mental flux. The problem with this theory is the term "blind." The variation needs to be blind in the sense that environmental interactions do not have an impact on the next variation of thoughts. Otherwise, the process would have to be understood as directed in which case the evolutionary model would not work. However, the blindness, if granted, prevents the environmental interactions from affecting the next variation. Thus, the selection process is not cumulative. (This is just a bizarre use of evolutionary theory, as far as I can see.)

Finally, teleosemantics employs evolutionary theory to explain the intentionality of thought and language. We come to have content in our thoughts and meaning in our words by way of an evolutionary process. To put it abstractly, "a mental state R of an organism O has content X if the fact that R indicates X has contributed to the survival of the evolutionary ancestors of O." Banay notes the reductionism of this approach. Even if it is cumulative, it reduces the philosophical question of intentional content to an evolutionary history. If we cloned a person, this theory could not explain how the clone (i.e., one without such history) could be said to have mental content. (I don't know if I buy that counterargument, but the point about reductionism is correct.)


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