Physical objects are conceptually imported into the situation as convenient intermediaries not by definition in terms of experience, but simply as irreducible posits comparable, epistemologically, to the gods of Homer . . . For my part I do, qua lay physicist, believe in physical objects and not in Homer's gods; and I consider it a scientific error to believe otherwise. But in point of epistemological footing, the physical objects and the gods differ only in degree and not in kind. Both sorts of entities enter our conceptions only as cultural posits.
Willard Van Orman QuineTheory may be deliberate, as in a chapter on chemistry, or it may be second nature, as in the immemorial doctrine of ordinary enduring middle-sized physical objects.
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 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 QuineThe strategy of semantic ascent is that it carries the discussion into a domain where both parties are better agreed on the objects (viz., words) and on the main terms connecting them. Words, or their inscriptions, unlike points, miles, classes and the rest, are tangible objects of the size so popular in the marketplace, where men of unlike conceptual schemes communicate at their best. The strategy is one of ascending to a common part of two fundamentally disparate conceptual schemes, the better to discuss the disparate foundations. No wonder it helps in philosophy.
Willard Van Orman Quine