How can we understand the world as a whole instead of separate natural and human realms? Joseph T. Rouse proposes an approach to this classic problem based on radical new conceptions of both philosophical naturalism and scientific practice. Rouse begins with a detailed critique of modern thought on naturalism, from Neurath and Heidegger to Charles Taylor, Thomas Kuhn and W.V.O. Quine. He identifies two constraints central to a philosophically robust naturalism: it must impose no arbitrarily philosophical restrictions on science, and it must shun even the most subtle appeals to mysterious and supernatural forces. Thus a naturalistic approach requires philosophers to show that their preferred conception of nature is what scientific inquiry discloses, and that their conception of scientific understanding is itself intelligible as part of the natural world. Finally, Rouse draws on feminist science studies and other recent work on causality and discourse to demonstrate the crucial role that closer attention to scientifc practice can play in reclaiming naturalism.