In search of counter-examples: Deductive rationality in human reasoning

Walter Schroyens*, Walter Schaeken, Simon Handley

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

65 Citations (Scopus)


Dual-process theories come in many forms. They draw on the distinction between associative, heuristic, tacit, intuitive, or implicit processes (System 1) and rule-based, analytic, explicit processes (System 2). We present the results of contextual manipulations that have a bearing on the supposed primacy of System 1 (Stanovich & West, 2000). Experiment 1 showed that people who evaluated logically valid or invalid conditional inferences under a timing constraint (N = 56), showed a smaller effect of logical validity than did people who were not placed under a timing constraint (N = 44). Experiment 2 similarly showed that stressing the logical constraint that only inferences that follow necessarily are to be endorsed (N = 36) increased the size of the validity effect, as compared to that of participants (N = 33) given the standard instruction to make "logical" inferences. These findings concur with the thesis in dual-processing frameworks that "Rationality-2 processes" (Evans & Over, 1996), "test procedures" (Chater & Oaksford, 1999), or "conclusion validation processes" (Johnson-Laird & Byrne, 1991; Schroyens, Schaeken, & d'Ydewalle, 2001) serve to override the results of System 1 processes.

Original languageEnglish
Pages (from-to)1129-1145
Number of pages17
JournalQuarterly Journal of Experimental Psychology Section A: Human Experimental Psychology
Volume56 A
Issue number7
Publication statusPublished - Oct 2003
Externally publishedYes


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