There has been a flurry of attention recently to the notion of a “poverty of the stimulus” argument in moral development. Briefly, the “Argument from the Poverty of the Stimulus” (”APoS”) was advanced by Noam Chomsky in support of his theory regarding an innate (”nativist”), universal human grammar, on which children draw as they learn language. (The argument has a formal structure, but it basically consists in the observation that the specific grammar of the particular language the child is exposed to is underdetermined by the stimulus the child receives - the sentences the child hears from others. Given a limited set of inputs, a variety of possible grammatical structures capable of producing those sentences could be deduced, so the child cannot learn one particular language from that input; instead, the child learns the one language that is capable of generating the set of sentences it has heard and which is possible under the set of universal grammatical rules hardwired into its brain. When it has heard enough sentences, only one plausible grammatical structure will be available from within the universal grammar the child possesses, although many possible grammars could still have been deduced if that constraint were not present. The existence of the universal grammar is required to make accurate language acquisition possible in spite of the poverty of the stimulus, and therefore the fact that language is acquired at all is evidence for such a universal grammar and therefore the truth of the nativist theory of language.) The moral parallel is the idea that there is a universal, nativist moral sense. Just as the existence of hardwired language rules allows the child to generate new sentences, despite its exposure to impoverished language stimuli previously, so the nativist moral sense allows the child to make moral judgments regarding situations it has not already encountered. Just as the nativist language theory is a refutation of the empiricist school of language - holding that language skills are acquired essentially by behaviorist-style mimicry - the nativist moral theory is a refutation of the claim that moral judgments are culturally determined.

Adam Colber of Neuroethics & Law Blog has a good post, referencing an interesting recent journal article on the topic. Kyle Swan of Pea Soup had a more detailed discussion of the subject about 18 months ago (I just found the link after being “stimulated” by Colber’s post), which provides some excellent speculation and a very insightful comments thread. He also provides a useful bibliography, and links to a preceding series of posts on moral realism. There’s some excellent work going on over there at Pea Soup.

But what does this all cash out to?

First, there is evidence that young children make creative moral judgments. But this evidence can be interpreted in a variety of ways. (See Swan’s post, and the comments, linked above, for an overview.) The questions whether there is an innate moral judgment, and whether this is distinct from (a) sociobiological behavioral patterns that reinforce cooperation and “punish” defection, and so forth, and (b) nativist judgment regarding merely prudential matters, are still open as empirical issues. But let us assume that there is nativist moral judgment, and it is “really moral” in whatever sense (i.e., focuses on behavioral questions that we would recognize as moral rather than merely prudential or cultural) - what are we to make of that fact?

Swan’s first commenter hit it on the head by asking: “what are your thoughts about how an innate moral ability interfaces with normative ethics?”

An obvious reaction, and my first one, is to argue that it is irrelevant to working out what the right moral norms should be. Whatever nativist judgmental capacity there is is clearly evolutionarily driven, and as such is no more morally right than putative sociobiological drives toward promiscuity or rape in males, stereotypical sex preferences, or out-group xenophobia. It is at best evidence that certain moral evaluations, which is to say certain responses to certain perceived behaviors, were adaptive in early human social settings. It is likely that many such selected-for evaluative traits would continue to be adaptive in other forms of human society, but it is also likely that many would not be as social patterns changed and cultural evolution redefined the social/familial landscape. Inferring any normative implications is merely to indulge the same naturalistic fallacy as so much naive sociobiology does.

Identifying these innate moral “principles” or patterns (if in fact they exist), however, may offer an at least suggestive, possibly even presumptive, set of candidate norms ripe for further evaluation, in the way that Axelrod’s famous identification of the “tit for tat” strategy for the iterative Prisoner’s Dilemma spawned reams of theoretical bloviating. Surely it is not accidental that human infants, and some other primates, seem to intuitively react to “punish” those who take a disproportionate amount of communal resources, nor that people will commonly refuse highly unequal divisions of resources even to their own immediate cost. These behaviors reinforce social comity by discouraging “defection”. But not only are these norms adaptive in some way, they may arguably be part of the logically necessary framework of a stable civilized society (hence moral norms, on some kind of Social Contract theory), or at least conform to actual moral norms as worked out by some other means. They’re worth taking seriously even if not endorsing prima facie.

However, the “moral APoS” case, I think, goes beyond the observation that there are such hardwired patterns of behavior. It is the claim that there is an inborn ”generative grammar of morality” - not just particular learned evaluative responses but a suite of coherent “principles” that could be modeled as a nascent moral theory. If we regard adaptive moral patterns as as being, as it were, “contingently normative” - as candidate norms worthy of investigation - is this “theory” a candidate moral system? Or just another reason why “Nature, Mr. Allnut, is what we are put on this earth to rise above?”