Abstract
In the first edition of Language, Truth and Logic, Ayer defines an analytic proposition as one whose ‘validity depends solely on the definitions of the symbols it contains’. In the introduction to the second edition of the book, he defines it as a proposition that is ‘true solely in virtue of the meaning of its constituent symbols’. In this chapter, I spell out how the two formulations are to be understood and how they relate to each other. I discuss a problem that arises in connection with the question whether definitions are analytic or synthetic before elaborating Ayer’s conception of propositions and his explanation of the necessity of analytic truths. Furthermore, I respond to the idea that propositions such as ‘Nothing can be red and blue all over at the same time’ are true independently of what words mean and, hence, cannot be true in virtue of meaning.