First, he introduces the notion of propensity as the probabilistic incarnation of a disposition. He says QM equations may be describing something he calls a propensity field. He then says: “The only things that exist are propensity fields and the inter(actions) they produce.” The interactions are events, so the propensities fields exist “for” events. Then comes this good passage:
Such events are characterized generically as ‘actual events’, because they have definite properties once they exist, and are selections between distinct possibilities that are arrayed like a field. In quantum mechanics, these actual events are just the process of “reduction of the wave packet’ that physicists and philosophers have long discussed and sought for both theoretically and experimentally.
2. Jonathan Schaffer (who must be one of the best contemporary analytic metaphysicians) has another draft paper posted called: “The Internal Relatedness of All Things”. In it he explores another avenue for defending priority monism (in addition to those contained in this paper).
The key argument goes that if there is some internal relation among things in the cosmos (resulting from shared causal history, spatio-temporal relatedness or some other factor); if, in other words, you cannot perform a “free recombination” of parts; then, a logical chain of reasoning leads to the conclusion that the whole of the cosmos is prior to its parts.
I don’t see any reason to disagree with his reasoning given the premises. However, I do disagree with one of his seemingly not-very-controversial premises: that is, that the common conception of our concrete cosmos can be considered the object which plays the role of the “whole” in priority monism. The dependence of actual things is not only on adjacent actual things, but crucially on possibilia which go beyond the actual (local neighborhood) cosmos.