The Composition of Thoughts

What holds a proposition together? In this paper, we will be discussing the Fregean take on this issue, where the question becomes: What holds a thought together. Frege's perspective is distinctive, we shall argue, in that it connects the composition of thoughts to their semantic role; thoughts cohere by being simultaneously what is expressed by sentences, and that which determines truth. Our narrative will follow a roughly historical course, charting the consequences of an initial tension in Frege's conception of the relation of content (Inhalt) to composition, to its resolution with the identification of content as sense and reference. The problem facing Frege is that he must make good on an explanation of why "The Evening Star is a planet" and "The Morning Star is a planet," have different contents; this is required for the proper operation of the Begriffsschrift, that is, of Frege's logic, which requires that we can discern that different thoughts have been proven on the basis of their forms. Frege's insight in providing the explanation - that the content of a sentence is not to be identified with its meaning (truth-value) - is as profound today as it was then. What Frege saw was that while the composition of one part of content - reference - is functional (concepts are characteristic functions), the composition of the other part - thought - is, in effect, linguistic, consisting of constituents that have a cognitive characteristic, i.e. modes of presentation. The explanation then follows: thoughts composed of different parts are different thoughts; contents that contain different thoughts are different contents; thus, "The Evening Star is a planet" and "The Morning Star is a planet," have different contents, as do, importantly, "2+2 = 4" and "3+1 = 4". Although our exegesis will be Fregean, its relevance to other conceptions of propositions and their coherence will be apparent in the dialectic.