This study compared Cosmides's (1989) social contract theory with Cheng & Holyoak's (1985) pragmatic reasoning schema theory as accounts of the thematic content effect in the Wason selection task. The former explains the effect in terms of an innate algorithm, whereas the latter explains it in terms of learned schemata. Cosmides prepared a “switched rule,” in which an antecedent and a consequent in the original conditional rule were interchanged so that the innate algorithm could not be applied while the pragmatic reasoning schema could. She found that the effect disappeared, and concluded that the effect is not produced by the pragmatic reasoning schema. However, the context attached to the switched rule revealed that this rule could hardly be interpreted as a permission rule, which could invoke a pragmatic reasoning schema. We made small modifications in Cosmides's switched rule and its context so that this rule could be interpreted as an obligation rule, which could also invoke a pragmatic reasoning schema. The cost-benefit relation in the context was held essentially unchanged so that the innate algorithm could not be applied. As a result, the thematic content effect appeared for the switched rule as well. This finding favors the pragmatic reasoning schema theory over the social contract theory, and thus largely reduces the plausibility of the hereditary account of reasoning ability. It was stressed that especially strong evidence is needed for hereditary accounts because they might well be utilized to justify social prejudice and discrimination.