JT Paasch

In his early Reportatio, Walter Chatton (1290--1343) makes a proposal that appears to be a procedure based on paraconsistent logic games. Walter's procedure (as I interpret it) is able to determine whether one of a pair of opposite propositions is more compatible with another proposition. In particular, Walter believes his procedure can determine which of a pair of counter-possible propositions is more compatible with a selected factual proposition. Shortly after, Adam Wodeham (1298--1358) finds a crucial flaw in Walter's proposal. Apparently persuaded by Adam's critique, Walter weakens his view in his later Lectura. On the weakened view, Walter's procedure cannot handle counter-possible propositions. But it can determine whether one of a pair of opposite factual or counter-factual propositions is more compatible with a selected factual proposition.

Scotus's theory about sameness and distinction is sometimes analyzed under the heading of identity. For instance, the formal distinction might be characterized as a weak kind of identity. I argue that the formal distinction cannot be a kind of identity at all. Instead, it falls under the heading of mereology. My claim is that Scotus believes not in different kind of identities, but rather in different kinds of mereological fusions. In this paper, I survey some standard texts where Scotus presents his theory, and I formalize it with a first-order mereological theory that directly models Scotus's claims. This is an adequate formalization, I think, because certain claims characteristic of Scotus's view are theorems in this theory, e.g., that the formal distinction is irreflexive, symmetrical, and intransitive. I also build a modal theory on top of the first-order theory, in order to directly capture a claim of Scotus's regarding separability. This modal extension is also adequate, because another characteristic claim of Scotus's turns out to be a theorem in the modal theory: namely, that fusions composed of formally distinct parts are inseparable. A final indicator that this formalization is adequate comes from the fact that it handles examples well, even the "hard cases." I discuss examples of fusions, in particular the Trinity, which can be analyzed in a straightforward mereological way using this theory. I conclude by pointing out that objections which claim that mereological accounts of the Trinity violate divine simplicity beg the question.

In Metaphysics 5.11, Aristotle says some things are naturally prior to others in the sense that the ones can exist without the others but not vice versa. In the 14th century, Scotus and Ockham offered different accounts of this. In this paper, I construct a semantic model for each of their theories. On the Scotist theory, expressions of the form " α is naturally prior to β " can be evaluated against a tree of states labeled with causal transitions. On the Ockhamist theory, such expressions can be evaluated against a branching tree of times.

Powers and dispositions seem to be perfectly real features of things. For instance, wine glasses are fragile, sugar is soluble, dry twigs are combustible, and so on. But what exactly are powers and dispositions like “fragility” or “solubility”? Are they “things”? Do they have parts and take up space? Where are they located? And how are they connected to the other features of their possessors? In this paper, I examine the scholastic debate about this, and I find three separate theories. First, Aquinas proposes a “two-category” theory: there are categorical entities, and there are dispositional entities in the world. Second, Henry of Ghent proposes a “two-aspects” theory: there are just categorical entities in the world, but they can have both a categorical aspect and a dispositional aspect. Third, Duns Scotus and William Ockham propose a “one-category” theory: there are just categorical entities and no dispositional entities in the world, and “powers” or “dispositions” are nothing more than the categorical parts and materials of things that cause the various effects we see around us.

Priority and posteriority are about ordering: the prior comes before the posterior. In the 14th century, Latin scholastics discussed different types of ordering. They asked: what types of priority are there, and how should they be defined? I examine William Ockham's analysis of two kinds: (1) priority in time and place, and (2) natural priority. For Ockham, objects $x$ and $y$ are ordered by time or place when they correspond to sequential times or places $u$ and $v$. Crucially, in order for $x$ to be prior to $y$, $x$ must correspond to $u$ by itself, without $y$. Regarding natural priority, Ockham defines it like this: $x$ is naturally prior to $y$ iff $x$ can exist without $y$ but not vice versa. Ockham sharply distinguishes this from causal priority, and that has a number of consequences. (1) Things can be naturally ordered, even if there is no causal connection between them. (2) Necessary things cannot be naturally ordered. They must be naturally simultaneous. (3) Mutually separable items cannot be naturally ordered either. (4) Natural priority is not a type of dependence.

In Aquinas on Human Self-Knowledge (2014), Therese Scarpelli Cory examines what Aquinas has to say about the knowledge that humans have of themselves. Crucially, Aquinas seems to take it as a given that humans have a first person perspective. I take issue with this. If the human mind functions as Aquinas thinks it does, it is far from clear how it could be aware of itself in a first-person way. To show this, I model the human mind by constructing an abstract machine that functions in much the same way that Aquinas thinks the mind functions, and then I show that this machine cannot acquire anything like the sort of self-awareness Aquinas thinks the mind has.

It is often said that Scotus and Ockham made significant contributions to the debate about universals and individuation. I argue that no clear view of their theories about properties has emerged. On the contrary, there are deep ambiguities and technical confusions in both the primary and secondary literature. In this paper, I try to outline some of the more important ambiguities and confusions in as clear a way as I can.