Wolff and the Logic of the Human Mind

This chapter addresses the issue of Wolff’s alleged psychologism by offering a historical and systematic reconstruction of his doctrine of natural logic, which captures his mature views on the relation between logic and psychology. The long gestation of this doctrine began in 1705 with Wolff’s re-evaluation of syllogism. The subsequent discovery that syllogism also informs all of our inferential processes gradually led him to the idea that there is a logic embedded in the human mind which determines the laws of thought. Wolff had metaphysical reasons to ascribe a syllogistic structure to human reasoning. Endorsing mechanism, he deemed it possible to describe the mind as a machine governed by a set of fixed laws, and took the rules of syllogistics to be the only plausible candidate for the role of genuine laws of thought. This suggests that a fundamental assumption of modern psychology – the assumption that there are psychological laws – owes something to both early modern mechanism and the doctrine of natural logic.