Our acceptance of an ontology is, I think, similar in principle to our acceptance of a scientific theory, say a system of physics;we adopt, at least insofar as we are reasonable, the simplest conceptual scheme into which the disordered fragments of raw experience can be fitted and arranged.
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 QuineThe familiar material objects may not be all that is real, but they are admirable examples.
Willard Van Orman QuineUnscientific man is beset by a deplorable desire to have been right. The scientist is distinguished by a desire to be right.
Willard Van Orman QuineSome may find comfort in reflecting that the distinction between an eliminative and an explicative physicalism is unreal.
Willard Van Orman QuinePhysical 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 Quine