Ayer published Language, Truth & Logic in 1936 when he was only 26 years old. He was part of the Vienna Circle; who were famously known for their philosophy of logical positivism. Logical positivism is a philosophical theory that considers significant only those non-tautological propositions that can be analyzed using the tools of logic into elementary propositions or that are empirically verifiable. He therefore rejects metaphysics, theology and sometimes ethics as meaningless. In Language, Truth & Logic, Ayer proposes his own version of the verification principle. It is by this principle of verification that these philosophers, including Ayer, evaluate whether propositions are meaningful or not. Furthermore, it is in the principle of verification and in the idea of ​​the analytic-synthetic distinction that the heart of Ayer's philosophy rests. Analytical propositions are propositions that are true or false only in virtue of their meaning, and synthetic propositions are propositions that are true or false in virtue of how the world is. Ayer's logical positivist position and the verification principle are flawed and unreliable, as demonstrated by many criticisms ranging from the self-refuting nature of the verification principle to Quine's collapse of the analytic-synthetic distinction. To begin with, Ayer's verification principle goes as follows: “a sentence is factually significant for a given person, if, and only if, he knows how to verify the proposition he intends to express, that is, if he knows what observations would lead him, under given conditions, to accept the proposition as true or reject it as false. If, on the other hand, the alleged proposition is of such a character that the assumption of its tr...... middle of paper...... revises our analytic beliefs and if we are testing them and they are not true by definition and are by experience, then the analytic-synthetic distinction collapses, which is fatal for logical positivists like Ayer. To summarize, as a logical positivist, Ayer held to a principle of verification according to which a proposition is factually significant if and only if it is a tautology or if it can be observed empirically under conditions that allow it to be made true or false. This verification principle is not only an impractical philosophy to follow due to its renunciation of ethics, aesthetics, and science, but it is also self-refuting since the verification principle cannot be verified and is not a tautology. It is for these reasons that Ayer's verification principle and logical positivism as a whole are rejected.