AAP 2026 CONFERENCE

It is generally accepted that Leibniz’s a posteriori argument which seeks to establish that force, measured by mv2 rather than mv, is conserved in the universe, has direct bearing on his broader metaphysical agenda. Leibniz is not simply introducing a new physical quantity and an argument for its conservation. He seeks to furnish a metaphysical foundation of mechanical physics.

This aim, arguably, is even more patent in his a priori argument for the conservation of actio. As Leibniz writes to De Volder, this argument is the “gate” through which one is to pass to the right metaphysics. I offer to bring into relief the metaphysical significance of the concept of intensity (intensio) in Leibniz’s a priori argument. Leibniz argues that quantity of actio is a product of intensity and extensity (extensio). Intensity is either velocity (when extensity is space) or square of velocity (when extensity is time). When taken in the latter sense, I argue, intensity receives a metaphysical inflection. Scholars have traced this notion to the medieval language of latitudo formarum. I contend that it denotes a degree of primitive activity constitutive of a singularity of substance, akin to Scotus’s notion of intensity as a degree of being’s perfection.