# Quote — A.J. Ayer, Language, Truth and Logic

> The criterion which we use to test the genuineness of apparent statements of fact is the criterion of verifiability. We say that a sentence is factually significant to any given person, if, and only if, he knows how to verify the proposition which it purports to express — that is, if he knows what observations would lead him, under certain conditions, to accept the proposition as being true, or reject it as being false.

- Author: [A.J. Ayer](https://www.leafyquotes.com/aj-ayer.md)
- Book: [Language, Truth and Logic](https://www.leafyquotes.com/aj-ayer/language-truth-and-logic.md)
- Page: 16
- Source: [Wikiquote](https://en.wikiquote.org/wiki/A._J._Ayer#Language,_Truth,_and_Logic_(1936)) ([CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0/))
- Quote page: https://www.leafyquotes.com/aj-ayer/language-truth-and-logic/the-criterion-which

## More from this book

> The traditional disputes of philosophers are, for the most part, as unwarranted as they are unfruitful. The surest way to end them is to establish beyond question what should be the purpose and method of a philosophical enquiry. And this is by no means so difficult a task as the history of philosophy would lead one to suppose. For if there are any questions which science leaves it to philosophy to answer, a straightforward process of elimination must lead to their discovery.

[Quote page](https://www.leafyquotes.com/aj-ayer/language-truth-and-logic/the-traditional-disputes.md)

> The problem of induction is, roughly speaking, the problem of finding a way to prove that certain empirical generalizations which are derived from past experience will hold good also in the future. There are only two ways of approaching this problem on the assumption that it is a genuine problem, and it is easy to see that neither of them can lead to its solution.

p. 49 — [Quote page](https://www.leafyquotes.com/aj-ayer/language-truth-and-logic/the-problem-of-induction.md)

> "I exist" does not follow from "there is a thought now." The fact that a thought occurs at a given moment does not entail that any other thought has occurred at any other moment, still less that there has occurred a series of thoughts sufficient to constitute a single self. As Hume conclusively showed, no one event intrinsically points to any other. We infer the existence of events which we are not actually observing, with the help of general principle. But these principles must be obtained inductively. By mere deduction from what is immediately given we cannot advance a single step beyond. And, consequently, any attempt to base a deductive system on propositions which describe what is immediately given is bound to be a failure.

p. 47 — [Quote page](https://www.leafyquotes.com/aj-ayer/language-truth-and-logic/i-exist-does.md)