Does Physics Need Metaphysics?

A number of thinkers both past and present have been skeptical of the role of metaphysics for science. The early modern philosopher David Hume denigrated metaphysics as an attempt to “penetrate into subjects utterly inaccessible to the understanding,” while the Logical Positivists saw metaphysics as meaningless, wholly useless to scientific inquiry. In contrast to these thinkers stands the early modern philosopher Gottfried Wilhelm Leibniz. A mathematician and scientist himself, Leibniz developed a variety of metaphysical principles entailed centrally by his Principle of Sufficient Reason. Leibniz utilized these principles to address scientific topics of his day, including, but not limited to, the relative nature of space and the heliocentric model of the universe. Drawing on Leibniz’s diverse corpus, I will reconstruct his formulations of the Principle of Sufficient Reason, the Principle of Perfection, and the Principle of the Identity of Indiscernibles, providing the intellectual context for their development. I will then argue through examples that his metaphysical principles illustrate the utility of metaphysics for natural science, for they can be used to both ground the logical coherence of the discipline of physics and serve as practical methodological guides for theory development and selection.