Cosmides, Wason, and Johnson-Laird, among others, have suggested evidence that reasoning abilities tend to be domain specific, insofar as humans do not appear to acquire capacities for logical reasoning that are applicable across different contexts. Unfortunately, the significance of these findings depends upon the specific variety of 'logical reasoning' under consideration. Indeed, there seem to be at least three grounds for doubting such conclusions, since: (1) tests of reasoning involving the use of material conditionals may not be appropriate for representing ordinary thinking, especially when it concerns causal processes involving the use of causal conditionals instead; (2) tests of domain specificity may fail to acknowledge the crucial role fulfilled by rules of inference, such as modus ponens and modus tollens, which appear to be completely general across different contexts; and, (3) tests that focus exclusively upon deductive reasoning may misinterpret findings involving the use of inductive reasoning, which is of primary importance for human evolution.
The general subject of this paper is the testability of hypotheses about human rationality within the context of theories of evolutionary psychology. The specific example that I shall discuss is a research program that extends from studies in the psychology of reasoning by Wason and Johnson-Laird to the advocacy of Darwinian algorithms by Cosmides and Tooby. The findings that have emerged from this research seem to support the view that human reasoning is governed by domain-specific psychological mechanisms, where these mechanisms might even preempt the possibility of human rationality.
The question I want to examine should not be misunderstood. I am not asking the question, (Q1)
Can rationality be adaptive?
This is an important philosophical question about the potential benefits that might accrue, from an evolutionary point of view, if human beings were rational. Presumably the answer to this question is "Yes!" The question I am asking instead is this, (Q2) Can adaptations be rational?