Our talk of external things, our very notion of things, is just a conceptual apparatus that helps us to foresee and control the triggerings of our sensory receptors in the light of previous triggering of our sensory receptors.
Willard Van Orman QuineDifferent persons growing up in the same language are like different bushes trimmed and trained to take the shape of identical elephants. The anatomical details of twigs and branches will fulfill the elephantine form differently from bush to bush, but the overall outward results are alike.
Willard Van Orman QuinePhysics investigates the essential nature of the world, and biology describes a local bump. Psychology, human psychology, describes a bump on the bump.
Willard Van Orman QuineFor me the problem of induction is a problem about the world: a problem of how we, as we are now (by our present scientific lights), in a world we never made, should stand better than random, or coin-tossing chances changes of coming out right when we predict by inductions. . . .
Willard Van Orman Quine