Gary Marcus: NYU Psychology

In fields ranging from reasoning to linguistics, the idea of humans as perfect, rational, optimal creatures is
making a comeback – but should it be? Hamlet’s musings that the mind was “noble in reason …infinite in
faculty” have their counterparts in recent scholarly claims that the mind consists of an “accumulation of
superlatively well- engineered designs” shaped by the process of natural selection (Tooby and Cosmides,
1995), and the 2006 suggestions of Bayesian cognitive scientists Chater, Tenenbaum and Yuille that “it
seems increasingly plausible that human cognition may be explicable in rational probabilistic terms and that,
in core domains, human cognition approaches an optimal level of performance”, as well as in Chomsky’s
recent suggestions that language is close “to what some super-engineer would construct, given the
conditions that the language faculty must satisfy”.

In this talk, I will I argue that this resurgent enthusiasm for rationality is misplaced, for three reasons. First, I
will suggest that recent empirical arguments in favor of human rationality rest on a fallacy of composition,
implicitly but mistakenly assuming that evidence of rationality in some (carefully analyzed) aspects of cognition
entails that the broader whole (i.e. the human mind in toto) is rational. In fact, establishing that some particular
aspect of cognition is optimal (or perfect, or near optimal) is not tantamount to showing that the system is a
whole is; current enthusiasm for optimality overlooks the possibility that the mind might be suboptimal even if
some (or even many) of the components of cognition have been optimized. Second, I will argue that there is
considerable empirical evidence (most well-known, but rarely given due attention in the neo-Rationalist
literature) that militates against any strong claim of human cognitive perfection. Finally, I will argue that the
assumption that evolution tends creatures towards rationality or “superlative adaptation” is itself theoretically
suspect, and ought to be considerably tempered by recognition of what Stephen Jay Gould called “remnants of
history”, or what might be termed evolutionary inertia.

I will close by suggesting that mind might be better seen as what engineers call a kluge: clumsy and
inelegant, yet remarkably effective.