In this paper I address two concerns with Kelly Trogdon’s grounding mechanism view, i.e. the idea that metaphysical explanation can be modeled on causal-mechanical explanation. The first concern threatens to undermine the unity that grounding-mechanical explanations imposes on metaphysical explanation; and the second concern requires the grounding mechanic to put forth a formal condition on grounding-mechanical models. After having discussed both of these, I provide a solution to the first and argue that the second concern is unwarranted.

Metaphysical explanations, unlike many other kinds of explanation, are standardly thought to be insensitive to our epistemic situation and so are not evaluable by cognitive values such as salience. I consider a case study that challenges this view. Some properties are distributed over an extension. For example, the property of being polka-dotted red on white, when instantiated, is distributed over a surface. Similar properties have been put to work in a variety of explanatory tasks in recent metaphysics, including: providing an (...) analysis of change, giving to presentists truthmakers for past claims; giving to priority monists an account of basic heterogeneous entities; and giving to friends of extended simples an explanation of how an extended simple can enjoy qualitative variation. I argue that such explanations exhibit salience failure. How ought we represent the semantics of salience? Differences in linguistic stress induce semantic differences similar to the semantic differences induced in explanations by differences in salience, and I will draw an analogy with linguistic theories of focus sensitivity to sketch how one might model the role of salience in these kinds of explanations. I end with a few tentative conclusions about the role of cognitive values in metaphysical explanations. Some theorists view the citation of a ground as a sufficient explanation. If certain explanations appealing to distributed properties exhibit attenuated salience, then arguably the mere citation of a ground does not always provide an adequate explanation. (shrink)

According to presentism, everything that exists is present. According to the truthmaker principle, for every true proposition there is a truthmaker – an entity that suffices for the truth of that proposition. According to realism about the past, there are true propositions about the past. Together these claims necessitate presently existing truthmakers for truths about the past (presentist truthmakers). Cameron (2010) argues that temporal distributional properties (TDPs) can play the role of presentist truthmakers. Corkum (2014) argues that they cannot. I (...) argue against Corkum’s objections. In §2, I introduce and outline the motivation for TDPs. In §3, I show that unless TDPs are stipulated to be fundamental, as Cameron does, they can be reduced to temporal non–distributional properties, which are unable to play the role of presentist truthmakers. In §4, I argue against Corkum’s two objections to Cameron’s stipulation. Corkum’s first objection is that Cameron has no grounds on which to stipulate that TDPs are fundamental, and that the reducibility of TDPs to temporal non–distributional properties (as discussed in §3) shows that they are not. I argue that the burden of proof is not on Cameron to argue that TDPs are fundamental, but on Corkum to argue that they are not, and that to argue from the reducibility of TDPs to their non–fundamentality is to beg the question against Cameron: the reduction is only possible once their non–fundamentality is assumed. Corkum’s second objection is that if Cameron is allowed to stipulate that TDPs are fundamental in order to escape objections, then Bigelow's (1996) account is allowed to make the same move, rendering Cameron’s account redundant. I argue that the cases are asymmetric: the alternative account faces a legitimate objection whilst Cameron’s account does not. (shrink)