"Dedicated as they were to the understanding of faith, our theologians accepted without criticism a great deal of ready-made philosophical and scientific knowledge that had no necessary relation to Christian revelation -- and, be it noted, these are precisely the dead and antiquated parts of their work, which we have absolutely no reason to preserve." -- Etienne Gilson, "Historical Research"
I have been trying, apparently without success, to convince the Thomists at Ed Feser's blog of this point, especially concerning the clearly antiquated doctrine of the division of life into non-sentient plants and sentient animals. Forget that this division totally ignores fungii, which are neither plants nor animals, it is also entirely dependent upon "movement" being defined as "movement at the pace at which humans move." Plants move around plenty, just more slowly than we do. And this antiquated division must classify single-celled organisms as "animals," since, seen under a microscope, they are clearly moving around, hunting, and so forth. But since plants evolved from such single-celled creatures, that would mean that at some point in their evolution, they "passed out" and lost sentience!
It is entirely understandable that Aristotle or Aquinas accepted this division. But today, we have a wealth of research showing us just how active plants are. Both Aristotle and Aquinas would have changed their view in the face of this research. It does their followers no credit that they will not do so.