Some have said that the thesis [of indeterminacy] is a consequence of my behaviorism. Some have said that it is a reductio ad absurdum of my behaviorism. I disagree with this second point, but I agree with the first. I hold further that the behaviorism approach is mandatory. In psychology one may or may not be a behaviorist, but in linguistics one has no choice.
Willard Van Orman QuineOur 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 Quine