Re 1: depends on whether you're interested in the essence of the species as it's present in populations made up of individual animals (while Aristotle thought these were eternal, it turns out he was wrong), or the essence considered as an exemplar cause in the mind of God (which is eternal, full stop).

Re 2: in what sense are you talking here? Strictly speaking, an accidental change is one that leaves the substance intact, so in a biological context, accidental change occurs only within the lifetime of a single organism. "Accidental changes" cannot accumulate through multiple generations, for the simple reason that there's no one organism persisting through multiple generations. Reproduction is, as the generation of a new organism, always a substantial change. The question is whether or not the parents and child will share the same substantial form. St. Thomas himself was perfectly willing to countenance the notion of a "corruption of the seed" resulting in offspring incapable of attaining the form of the parent, and relied on this notion to explicate the views of Empedocles in a commentary on Aristotle's Physics. Adapting the idea to interpret Darwin would be child's play.

Last edited by Dave (7/20/2018 8:24 pm)