不確定性と不完全決定性―翻訳の不確定性のテーゼの一解釈―

Abstract

The author attempts to make clear Quine's indeterminacy thesis by focussing upon the difference between the notions of underdetermination and of indeterminacy. While the notion of underdetermination is an epistemological notion, that of indeterminacy is not only an epistemological one but also an ontological one. And this ontological element is the following : while there is fact of the matter for physical theories to be right or wrong about, there is no fact of the matter for manuals of translation to be right or wrong about. A physical theory is underdetermined by the totality of available evidence, that is, there can be several physical theories which are equally compatible with the evidence but incompatible with each other. Hence if we undertake a radical translation, we can construct several manuals of translation which are equally compatible with the evidence but mutually incompatible, because all the evidence we have is a correlation of a native observation sentence with an observation sentence (or observation sentences) of our own language which has/ have the same stimulus meaning (same truth condition), and because these observation sentences constitute the evidence for the physical theories of the native and of our own at the same time. Thus a manual of translation is underdetermined by the totality of available evidence. Then, what is the difference between underdetermination and indeterminacy? It is an ontological difference. Since the physical state of the native remains one and the same while manuals of translation ascribe mutually incompatible beliefs to him, there is no physical difference corresponding to the difference of the beliefs ascribed to him. Hence, there is no fact of the matter for manuals of translation to be right or wrong about.