Michael Polanyi's conceptions of tacit knowing and emergent being are used to correct a reductionism that developed from, or reacted against, the excesses of several Cartesian assumptions: (a) the method of universal doubt; (b) the emphasis on reductive analysis to unshakeable foundations, via connections between clear and distinct ideas; (c) the notion that what is real are the basic atomic substances out of which all else is composed; (d) a sharp body-mind substance dualism; and (e) the notion that the seat of consciousness can be traced to a point in the human body. The reductivist project in biology began with the emphasis Descartes put on the body as a machine. Polanyi reappropriates the machine metaphor to demonstrate how mechanistic explanations are not fully reductive. He shows how an eliminative materialism that would reduce mind to brain is unwarranted if either an interlevel mechanistic reduction or an intralevel successional reduction is posited. (Contains 20 notes.)