Chemical applications of statistical mechanics typically assume that the electronic partition function is trivial, as all members of the system are in the ground electronic state. When this approximation breaks down (example: electrical conductors), it is necessary to combine statistical mechanics and electronic structure theory to determine the electronic partition function. This composite theory is called a "finite-temperature" theory. The oldest finite-temperature theory is finite-temperature perturbation theory (FTPT). In 2013, Prof. Hirata asserted that the FTPT described in physics textbooks was incorrect because it failed basic sanity checks, and that the real FTPT needed to be found. This seminar reviews the chemistry literature of FTPT and the arguments over which one is "really" FTPT, a rare instance of a controversy in pure theory.