I have to admit to having taught students that essentialism - the belief that species have an essence and thus could not evolve - was prevalent prior to Darwin. This was something I got from reading the writings of Ernst Mayr. Now along comes John Wilkins who argues "essentialism in biology postdates Darwin, and was in fact due to the revival of Thomism among German and French speaking Catholic biologists who were reacting to the metaphysical views of people like Herbert Spencer and Ernst Haeckel." He notes that Aquinas' De ente et essentia [link] is the first example of the "argument from essence" (if I can coin a phrase) that he can find. He also notes that Aquinas' view was not a majority position.
Read John's post to find out why the myth of prevalent essentialism rose among, what he terms, "history-plundering evolutionists" [Insert pirate Arrrrrrrrrrrrrr here].
I've been following the whole back-and-forth between Chris, Brandon and John over the past few days and it is very enlightening!
Oh great! Now I have this vision of Mayr with an eye patch, and a parrot, saying "Why are systematists the best pirates? They just arrrrrrre..."
I won't sleep tonight.
If I was any good at Photoshop, I'd have to make a pic. But I'm not, so ...