Abstract

Dr. Brian T. Carl published a paper, “Thomas Aquinas on the Proportionate Causes of Living Species,” in which he defends a thesis that the principle of proportionate cause, as understood by Aquinas, cannot be used to contradict the modern theory of biological evolution. This rejoinder explores thoroughly Carl’s argument, specifically his idea that spontaneous generation serves as a model to explain causality in biological evolution. It is shown that Aquinas indeed accepts proportionate causes in spontaneous generation, but this fact cannot be extrapolated to modern evolutionary theories. The origin of new species after creation was completed is not a straightforward thesis in Aquinas; rather Thomas sees it as a possible exception, which contradicts the evolutionary origin of the vast majority of species. Additionally, Carl misses the major point that in Aquinas the origin of new species belongs to the work of creation rather than the natural operation of secondary causes.