Therefore, the presence of more than one substantial form in such a being would undermine its substantial unity.
Third, Scotus holds that some substances have more than one substantial form (Ordinatio 4, d. 11, q. 3, n. 54).
Others, and most famously Aquinas and his followers, hold that a living thing can only have one substantial form and therefore only one soul (Pasnau 2002, 126 30).
There is natural transubstantiation when a substitution of one substantial form for another takes place, but the subject-matter remains the same.
Heatedly debated in the 1270s and 1280s both at Paris and Oxford was the question concerning whether there is one or more than one substantial form in one substance, and especially in a human being.
One substantial form for the corporeality of the body, perhaps one to account for the vegetative activities of the human being, yet another for the animal activities, and then a final one for the intellectual activities of the human being.
But as Scotus elaborates his views on form and matter, he espouses three important theses that mark him off from some other philosophers of his day: he holds that there exists matter that has no form whatsoever, that not all created substances are composites of form and matter, and that one and the same substance can have more than one substantial form.
According to the other, Aristotle's arguments in Ζ.13 are not intended to show that no universal is a substance, tout court, but some weaker thesis that is compatible with there being only one substantial form for all of the particulars belonging to the same species.
From this it further happens that in the same indivisible boundary of matter there would be, at the same, time two specific substantial forms with respect to something that is indivisible in extension".
According to one, Aristotle's substantial forms are not universals after all, but each belongs exclusively to the particular whose form it is, and there are therefore as many substantial forms of a given kind as there are particulars of that kind.
