The Context: The Question of Truth Bearers

Abstract

In Frege’s work on the foundations of logic and mathematics, psychologism is one of his major objects of criticism. Psychologism regards logic as a part of psychology and ideas as truth-bearers. Already in the first paragraph, Frege makes sure to draw a clear line between logic and psychology:

[I]t falls to logic to discern the laws of truth. […] From the laws of truth there follow prescriptions about asserting, thinking, judging, inferring. And we may very well speak of laws of thought in this way too. But there is at once a danger here of confusing different things. People may very well interpret the expression ‘law of thought’ by analogy with ‘law of nature’ and then have in mind general features of thinking as a mental occurrence. A law of thought in this sense would be a psychological law. And so they might come to believe that logic deals with the mental process of thinking and with the psychological laws in accordance with which this takes place. That would be misunderstanding the task of logic, for truth has not here been given its proper place. […] In order to avoid any misunderstanding and prevent the blurring of the boundary between psychology and logic, I assign to logic the task of discovering the laws of truth, not the laws of taking things to be true or of thinking. (Frege, 1918a, pp. 58–9)