チャーマーズの「意識しない心」について - 思考可能性と意識の不在をめぐる問い -

Abstract

"David Chalmers claims that the nature of consciousness as a subjective quality constitutes an independent subject area and that its existence cannot be reduced to anything else. In particular, reductive explanations to physical theories as well as functionalism about mental states are hopeless for this purpose (perhaps they assume the existence of the conscious mind, in that failing to explain what we seek to understand about its very nature). His argument for mind-body dualism, which is supposed to sustain the claim above, proceeds as follows: 1) what is conceivable is possible; 2) There is at least one conceivable world where one’s physical duplicate has no consciousness, which is called a zombie-world; therefore, 3) the zombie-world is possible; 4) if it is possible, then physicalism or materialism is false; therefore, 5) physicalism is false. The central concern of this essay is to critically examine Premises 1) and 2). Concerning Premise 1), which I shall call the “Conceivability-Possibility Thesis, ” some precedent arguments based on similar theses can be found throughout the history of western philosophy (e.g. the Cartesian argument for mind-body dualism and Hume’s denial of the reality of causality), and many contemporary philosophers discuss their validity and force (e.g. van Cleve, 1983 & Yablo, 1993). It should be noted, however, that Chalmers uniquely defends the thesis, as seen in his developed theory known as “epistemic two-dimensionalism, ” and I shall begin with its survey (Section 2 and 3). Through this examination, it will be realized that 1) and 2) are not independent premises, and that 1) can never be established as a general rule applicable to all cases until conceivability of the zombie-world is shown to be a priori. I shall argue that no such a priori reasoning for non-existence of consciousness is incomplete (Section 4). (Note also that if this is correct, the zombie case, pace Chalmers, will fall under the “twilight zone” in his terminology and even be in danger of becoming a counter-example to his Conceivability-Possibility Thesis. It therefore should be admitted either that conceivability of the unconscious mind is incomplete, or that the thesis that is expected to encompass something that is merely, or only allegedly conceivable, cannot be maintained. In effect, the zombie argument will turn out to be undone. Following this, responses to six possible objections will be set forth (Section 5)."