The question as to the place of Mind in Nature is a reformulation of the question as to the place of human beings in nature. T. H. Huxley's essay on 'Man's Place in Nature' * was an attempt to break down the distinction between human beings and animals by viewing our species in the light of biological evolution. For most people at least, Huxley settled the question of whether the existence of our species required a different sort of explanation than did the existence of other kinds of animals. But this result simply transferred the problem to philosophy. The question now became: granted that what is special about human beings was produced by the same sorts of causes as produced the special faculties of the other animal species, are these human facul ties nonetheless so different that there is a special, philosophical problem about their nature? Granted, in other words, that what we call "mind" came into the world by spatio-temporal mechanisms homogeneous with those which produced the rest of the world's contents, what is it that we call "mind"? Something which is simply a special case of the other physical things which emerged? Or something "irreducible" to the physical? This is a vague question because "irreducible" is a multiply am biguous word. Most discussions of "the mind-body problem" argue for reducibility or irreducibility by tacitly choosing a sense, or senses, of "reducible" favorable to their own side. There are many such senses, stretching along a spectrum between a purely causal sense at one end and a purely definitional sense at the other. Those inclined to reduce mind to matter like to think that Huxley's point that mind emerged from matter is enough to show that there can be no ontolo gical discontinuity. So this side employs a sense of "reducible" in which X's are reducible to Y's if all the causes of X's are Y's. Those inclined to proclaim the irreducibility of mind like to think that since you cannot communicate what tarragon tastes like by telling a story about molecules there obviously is an ontological discontinuity. So