What is it about sentences that expresses truth or falsity? Gottlob Frege is considered one of the fathers of analytic philosophy, but it's hard for someone with a general interest in philosophy to see much of his work as overtly philosophical. He did a lot of the work inventing modern symbolic logic, with an eye to providing a logical foundation for mathematics. But in doing this, he showed a philosophical agenda that was very influential for Wittgenstein and many others.
Frege is concerned with what it is about sentences that make them true or false. He's convinced that while our judgments about matters of fact are subjective, the matters of fact themselves are not. His objectivity is so extreme here that he considers abstract propositional entities, numbers, and meanings to be objectively real; they aren't just ideas you or I have in our heads, but are discovered and shareable between different people. He thinks that while a proper name refers to something in the world ("Dick Clark"), a sentence about that name ("Dick Clark is bad ass") correspondingly refers to THE TRUE, i.e. a weird metaphysical entity that all true sentences refer to. Smoke that, man!
Read these articles along with us:
"The Thought" (1918)
"On Sense and Reference" (1892)
"On Concept and Object" (1892)