The proposition that there is a purely causal explanation of subjective states of human consciousness is a philosophical one. The affirmation of such a proposition must be a premise to research. And the justification for such a premise will be found in part in the fundamental ontological assumptions of the researcher. By examining the assumptions of Rene Descartes, at the beginning of the scientific age, I hope to show a similar set of assumptions behind the thought of two recent contributors (...) to the debate, John Searle and Gerald Edelman. I will conclude that a crucial question is begged by all three. (shrink)