Modern science began as natural philosophy, an admixture of philosophy and science. It was then killed off by Newton, as a result of his claim to have derived his law of gravitation from the phenomena by induction. But this post-Newtonian conception of science, which holds that theories are accepted on the basis of evidence, is untenable, as the long-standing insolubility of the problem of induction indicates. Persistent acceptance of unified theories only in physics, when endless equally empirically successful disunified rivals are available, means that physics makes a persistent, problematic metaphysical assumption about the universe: that all disunified theories are false. This assumption, precisely because it is problematic, need...