Semantic essentialism holds that any scientific term that appears in a well-confirmed scientific theory has a fixed kernel of meaning. Semantic essentialism cannot make sense of the strategies scientists use to argue for their views. Newton's central optical expression "light ray" suggests a context-sensitive view of scientific language. On different occasions, Newton's expression could refer to different things depending on his particular argumentative goals - a visible beam, an irreducibly smallest section of propagating light, or a traveling particle of light. (...) Essentialist views are too crude to account for the richness and subtleties present in actual episodes of scientific debate and theory-change. (shrink)

Traditional logical empiricist and more recent historicist positions on the logic of discovery are briefly reviewed and both are found wanting. None have examined the historical detail now available from recent research on Darwin, from which there is evidence for gradual transition in descriptive and explanatory concepts. This episode also shows that revolutionary research can be directed by borrowed metascientific objectives and heuristics from other disciplines. Darwin's own revolutionary research took place within an ontological context borrowed from non evolutionary predecessors (...) with methodological objectives borrowed from and justified by their success in Newton's physics. The logic of discovery is not a special form of inference from observation to theory, but rather a theory of the rationality of research, including principles bearing upon the rational choice of problems, or epistemic objectives, and heuristic, or means to solving the problems. Such choices can be justified only locally in the context of a relatively stable background ontology and substantive epistemology, not globally for all science. (shrink)

In this paper I consider a cluster of positions which depart from the immortalist and dualist anthropologies of Rene Descartes and Henry More. In particular, I argue that John Locke and Isaac Newton are attracted to a monistic mind-body metaphysics, which while resisting neat characterization, occupies a conceptual space distinct from the dualism of the immortalists, on the one hand, and thoroughgoing materialism of Thomas Hobbes, on the other. They propound a sort of property monism: mind and body are distinct, (...) with distinct characteristics and functions, but are, nevertheless, ontologically interdependent. Consciousness ? the locus of personhood, and thus, a necessary condition for personal immortality ? is an embodied phenomenon; its preservation requires the life and proper functioning of the body. Dying with the dissolution of his body, then, man is a compound wholly mortal. Nevertheless, both Locke and Newton accepted the possibility of personal immortality; with Hobbes, both looked to the Biblical promise of bodily resurrection. For with the re-vitalization of the body ? and a subsequent restoration of consciousness and memory ? personal identity is preserved, even beyond the grave. (shrink)

In this paper I discuss Newton's first optical paper. My aim is to examine the type of argument which Newton uses in order to convince his readers of the truth of his theory of colors. My claim is that this argument is an induction by elimination, and that the Newtonian method of justification is a kind of “generative justification”, a term due to T. Nickles. To achieve my aim I analyze in some detail the arguments in Newton's first optical paper, (...) relating the paper with Newton's other writings in optics, and especially his early correspondence in defence of his theory of colors. (shrink)