But let's consider whether Aquinas and Scotus disagree.
We know the following:
Scotus thinks there are two conditions for a univocal concept.
1. to affirm and deny with respect to the same results in a contradiction.
2. It can be used as a middle term in a syllogism without there being a fallacy of equivocation.
Aquinas defines univocity (see for example Summa Ia q. 13 and De unioni verbi a. 2 ad 4) as when two things have the same name and the same definition. This is Aristotle's definition from the Categories.
Aquinas also thinks (Summa Ia q. 13 a.5?) that analogical concepts are such that they can serve as the middle term in a syllogism without there being a fallacy of equivocation.
Now some notes about the history of equivocity/univocity. We have seen Aristotle's view of univocity. His view of equivocity is when the name is the same but the definition is different. In the Metaphysics he admits of a kind of equivocity that is "focused" or has related meanings, and uses the health example. This is Aquinas' analogy. Aristotle's analogy shows up in the Ethics and consists of a proportion, and always involves four terms (A:B::C:D). Scotus' definition of univocity allegedly comes from Simplicius' commentary on Aristotle's categories (I say allegedly because I've never been able to find it. Of course, I haven't looked very hard either).
Scotus sees only two options: univocity or equivocity. There is no medium. Analogy is a subset of equivocity, and as such will result in a fallacy of equivocation. Aquinas sees three options: equivocity, univocity, and analogy. Mysteriously, he thinks that analogy is a medium between the extremes and so does not commit a fallacy of equivocation. I tend to side with Scotus on this point, given the history of the problem.
In rather annoying (perhaps, truly Scotistic?) fashion, Scotus also thinks there can be analogical concepts, and never bothered to attack Aquinas' notion of analogy (what may be important today was not necessarily seen as such in the 13th century), save in Collatio 23, which doesn't have a resolution. So we can fault Aquinas for confusing analogy with equivocity, and Scotus for not telling us how univocal concepts relate to analogical ones and for not analyzing Aquinas' position.
What does all this mean? Well, given the 700 year history of this debate, my readers should not be surprised that I arrive at no definitive conclusions. But if we ignore for the moment Aquinas' belief that analogical concepts avoid fallacies of equivocation and focus on his definition of univocity, a way of harmonization presents itself. For it is clear from Scotus' account that he is primarily interested in concepts, and there is no "real" correspondence between the univocal concept of being and being outside the mind. But Aquinas' definition of univocity concerns two things; and given all his other discussions of analogy in which it is clear that univocity is impossible because of the nature of the divine causality (ie., its equivocal), it's clear that Aquinas is primarily concerned with the "real", and that any analogical concepts are isomorphically related to their real foundations (hence, he has to say analogical concepts don't cause fallacies, because otherwise there would be no systematic theology, only mystical experience a la David Burrell's "theology is a dance"). So, to conclude, we could harmonize our medievals by the claim that they are in fact complementary, for Scotus thinks univocity is on the level of the concept, while Aquinas thinks that analogy is on the level of the real.
