Whitehead and others have decried the ,,bifurcation of nature, that is, the split between the world depicted by science, which lacks such phenomena as purpose, meaning, and value, and the world of human experience, which is largely constituted by those same phenomena. In order to guide our thinking about how this split might possibly be overcome, I propose three guiding principles, which I hope will be widely accepted: (1) The reality of the human world; (2) The cognitive excellence of empirical science; and (3) The unification of knowledge. All three of these principles are eminently reasonable, and yet they appear to form an inconsistent triad. Naturalism, as the metaphysical worldview extrapolated from empirical science, is distinguished from empirical science as such. I propose that the only way to reconcile the three guiding principles is to reform naturalism in such a way as to recognize the objective reality of biological purpose. Such a reform in the foundations of biology might then provide us with a foundation for reconstructing our view of the human world. The argument in support of this proposed reform proceeds in two stages. First, as pars destruens, I show that naturalism as usually construed is anyway untenable, because the two chief theories by means of which biological purpose is supposed to be reduced to mechanism - the theory of natural selection and the theory of cybernetic control - fail as reductive schemas because each theory tacitly presupposes purpose at a crucial point in its explanatory structure. Second, as pars construens, I discuss the possibility of using some concepts borrowed from nonlinear dynamics and condensed-matter physics as a way of directly representing biological purpose as a real, emergent phenomenon. Finally, I end with a brief reflection on the implications of the doctrine of ontological emergence for the principle of the unification of knowledge.