In 2006 Sharon Street published an article, “A Darwinian Dilemma for Realist Theories of Value,” which has been the subject of a considerable literature in reply. Her argument relies on the primary claim that our normative dispositions—that is, our dispositions to form certain normative beliefs rather than others—are (largely) selected because they have some natural property. For example, perhaps they contribute to reproductive success by promoting certain kinds of cooperation. But from the perspective of realism, accepting this claim defeats our epistemic entitlement to our normative beliefs, because we will come to be aware of the unlikely reliability of the processes that shaped those beliefs.

This is the Darwinian dilemma: the realist has either to deny the primary claim or to concede that her “normative judgments are, by her own lights, irrational.” She’s not arguing for skepticism or for the impossibility of ethical knowledge. Rather, she is trying to show that, if there is to be ethical knowledge, it has to be understood on an anti-realist model. Her point is that all that natural selection needs is our beliefs in the normative facts, not the normative facts themselves. If our normative and theological beliefs are largely the product of our evolutionary history, fitness-enhancing beliefs about morality and gods will be adopted, regardless of whether they are, in the realist sense, true or false. Even if a particular belief is false, it may promote genetic propagation.

This is the challenge. But there is a good response to it. Even if we grant that natural selection has given us normative belief-forming dispositions that are not truth-tracking, and that have in fact given us a mixture of “nasty” belief-forming dispositions and corresponding behaviors alongside other “nicer” ones, and even if we grant that therefore our normative beliefs are unreliable to the extent that they are given to us by natural selection, nothing follows about how many of our normative beliefs are formed in this way.

Consider the analogy with mathematical beliefs. To what extent do we have the ability to track truths about non-linear algebra? The point is that, even if we get our cognitive equipment from evolution, we can use that equipment to reach beliefs that are independent of adaptive value. It remains possible that cultural evolution has been operating to refine our normative stance in a truth-tracking way. If we use the phrase “cultural evolution” loosely, we can make the point that admitting a significant initial effect of biological evolution on belief formation does not license the conclusion that natural selection is the sole force in all our belief formation thereafter.

The initial effect of natural selection is still relevant, because, if we were given cognitive equipment that was hopelessly and permanently vitiated, then we could not hope to use this equipment to discriminate subsequently between the beliefs in the initial mixture that we should endorse and the ones we should reject. We would be, so to speak, fatally handicapped. But there is no reason to think our situation is hopeless in this way.

Are our current normative disposition all simply products of natural selection and not (partly or wholly) products of experience, reflection, and reasoning guided by moral reality as such? This is a metaphysical question, not one proper to science in its own domain. Ruse’s recognition of this separates him from Mackie. We need to distinguish the claims of science and the claims of “scientism,” which is the attempt, as Ruse puts it, to make science say everything. Metaphysical naturalism claims baldly that there is nothing beyond physical reality, but this is a claim that requires philosophical justification and is not within the proper sphere of science. Street’s argument does not give us any reason to believe that metaphysical naturalism is true.

Image: Australopithecus Afarensis, Lucy. C. Lorenzo. CC License.