Thomas Reid, Champion of Common Sense, on the Immaterial Souls of Vegetables
Eighteenth century Scottish "common sense" philosopher Thomas Reid never tires of flogging his opponents with their violations of common sense. Thus, it may seem surprising that he would write this:
[B]oth vegetables and Animals are United to something immaterial, by such a Union as we conceive between Soul and Body, which Union continues while the Animal or Vegetable is alive, & is dissolved when it dies (in Wood, ed., 1995, p. 218-219).
In other words, vegetables have immaterial souls -- or, if not souls exactly, immaterial parts analogous to souls. (Not to worry, there's no Vegetable Heaven [see p. 223].) Although Reid doesn't highlight this point or dwell upon it, it flows very naturally from his general system on which nothing material can be the source of its own movement (including growth).
Because of Reid's reputation as the great philosopher of common sense, I'm examining his work as a test case of the following empirical hypothesis, which I currently consider to be well supported: No philosopher has ever been able to construct a detailed and coherent metaphysics of mind that entirely respects our commonsense intuitions. Not even Reid could do so. (Shall we try G.E. Moore next?)
The conclusion I'm inclined to draw, partly on its own merits and partly as the best explanation of this fact about the history of philosophy, is that our commonsense metaphysical intuitions are, at root, incoherent. Thus, there is no way to build a detailed and coherent metaphysics of mind that entirely respects common sense, making it unsurprising that none of the brilliant minds in the history of philosophy have ever done so.
Update, October 3:
Several people have reminded me in the comments that in Reid's era it might not have been contrary to common sense to suppose that vegetables have some sort of vital essence not wholly material. Reid's remarks about the immaterial souls of vegetables need to be seen in light of that. Still: It's a leap from some sort of vaguely folk-approved vital essence to an immaterial soul (or vegetative soul), and Reid does use the word "soul"; and he contemplates the question of afterlife for vegetables; and his view on these issues is tangled up with his view that physical objects and events have no causal powers of their own but require the constant intervention of immaterial beings -- a view that he explicitly confesses to be at odds with what most ordinary people would accept.
So: I still hold my view that Reid is not wholly able to preserve common sense on this matter, but the issue is more complex than I made it seem above.