Verifiability Quotes

It is, therefore, possible to extend a partially specified interpretation to a complete interpretation, without loss of verifiability, [...] This fact offers the possibility of automatic verification of programs, the programmer merely tagging entrances and one edge in each innermost loop. (Robert Floyd)
Put in a nut-shell, my thesis amounts to this. The repeated attempts made by Rudolf Carnap to show that the demarcation between science and metaphysics coincides with that between sense and nonsense have failed. The reason is that the positivistic concept of 'meaning' or 'sense' (or of verifiability, or of inductive confirmability, etc.) is inappropriate for achieving this demarcation - simply because metaphysics need not be meaningless even though it is not science. In all its variations demarcation by meaninglessness has tended to be at the same time too narrow and too wide: as against all intentions and all claims, it has tended to exclude scientific theories as meaningless, while failing to exclude even that part of metaphysics which is known as 'rational theology'. View quote
Karl Popper
The criterion which we use to test the genuineness of apparent statements of fact is the criterion of verifiability. View quote
Alfred Jules Ayer
Lack of verifiability was a paranoiac's playground paradise. View quote
Malcolm Azania
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. View quote
Alfred Jules Ayer