The Received View: Piaget Dead on Deductive Reasoning

While some elements of Piaget's thought remain very much alive today, the consensus seems to be that at least one part has long been reduced to a carcass: the part according to which

Humans naturally develop a context-free deductive reasoning scheme at the level of elementary first-order logic.

As evidence that is generally regarded to be stone cold dead, one can do no better than Peter Wason's [Wason, 1995] relaxed remarks in his contribution to a recently published book [Newstead and Evans, 1995] written in his honor. Wason is credited with devising the seminal experiments that led to the rejection of (we will visit two of the experiments below), and the remarks in question arise from his retrospection on these experiments. For example, we read: ``The first formal experiments, done partly in Scotland, met with grave looks from dedicated Piagetians; the subjects' were clearly incompatible with `formal operations' " ([Wason, 1995], 296). Wason writes here and elsewhere as if has been long buried; most others in the psychology of reasoning follow suit. For example, the other contributors to the volume in question, each and every one of them, is likeminded: they either explicitly reject or presuppose the falsity of Piaget's .

In this short paper we present a prolegomenon for vindicating Piaget's affirmation of and its relatives. The paper is structured as follows. In section 2 we present four logic problems on which the vast majority of educated adult subjects do indeed exhibit poor performance: Wason's selection task and ``THOG" problem, a well-known and thoroughly studied invalid syllogism [Oakhill et al., 1989], and an ingenious fourth problem involving exclusive disjunction recently introduced by Johnson-Laird and Savary [Johnson-Laird and Savary, 1995]. In section 3 we briefly review the main responses that have developed in response to the experiments and data discussed in section 2. In section 4 we briefly present our response. In the final section, 5, we discuss empirical support for our response, garnered from S. Bringsjord's attempt to produce in students the reasoning ability Piaget believed would develop at the stage of ``formal operations." This discussion is accompanied by synoptic formal analysis of two of the problems presented in section 2.