CHEMISTRY IN KANT'S OPUS POSTUMUM

In his Metaphysische Anfangsgründe der Naturwissenschaft, Kant claims that chemistry is an improper although rational science. The chemistry to which Kant confers this status is the phlogistic chemistry of, for instance, Georg Stahl. In his Opus Postumum (OP), however, Kant espouses a broadly Lavoiserian conception of chemistry. In particular, Kant endorses Lavoisier's elements, oxygen theory of combustion, and role for the caloric. As Lavoisier's lasting contribution to chemistry, according to some histories of the science, was his emphasis on quantitative methods, Kant's assimilation of the chemical revolution raises the question: Did Kant continue to think of chemistry as an improper, although rational, science in OP? In this article, I answer this question affirmatively. I explain that a proper science requires a priori laws for the mathematical construction of its objects: the mere use of quantitative measurements is insufficient for the satisfaction of this requirement. Further, I argue, contra Burkhard Tuschling, that in OP Kant retains a central role for mathematical construction in the foundations of proper natural science. Finally, I contend that the prominent a priori components of chemistry discussed in OP—the aether and the enumeration of the elements—do not make chemistry into a proper science.