The problem of induction is, roughly speaking, the problem of finding a way to prove that certain empirical generalizations which are derived from pa… - A. J. Ayer

If now I…say "Stealing money is wrong," I produce a sentence which has no factual meaning — that is, expresses no proposition which can be either true or false. It is as if I had written "Stealing money!!" — where the shape and thickness of the exclamation marks show, by a suitable convention, that a special sort of moral disapproval is the feeling which is being expressed.

No moral system can rest solely on authority.

"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.