I’ve written a paper arguing that the truthmaker theorist has to be a priority monist, on pain of being committed to mysterious necessary connections. That is, if you think that for every true proposition there is an entity which couldn’t exist and that proposition be false then you should also think that there is only one fundamental existent, with every other entity being ontologically dependent on The One, otherwise you violate my suggested version of the Humean ban on necessary connections.
The full paper is here, and any comments will be much appreciated. But here’s the argument in outline. The first step is to identify when necessary connections are acceptable. A completely die-hard Humean would say: never. I’m interested in how to be less die-hard and still have a principled position (one that can be justified independently of considerations concerning truthmaker theory). One popular option is: necessary connections are bad when they’re between wholly distinct existents, but acceptable when they’re between distinct but not wholly distinct entities – i.e. entities that overlap. I don’t like that. In general, things have the parts they do, and belong to the complexes they do, as a matter of contingency; and if that’s the case then necessary connections between overlapping entities are as mysterious as necessary connections between wholly distinct entities. I suggest instead that necessary connections are acceptable iff there is an appropriate relationship of ontological dependence between the entities. I want to analyse ontological dependence in terms of truthmaking: B is ontologically dependent on A iff B exists in virtue of A’s existence, which is to say just that A is the truthmaker for the fact that B exists. In that case, it’s no surprise if the existence of A necessitates the existence of B – that just follows from truthmaker maximalism. With a caveat that I won’t go into here (but I do in the paper), I suggest we limit the necessary connections in our ontology to those where the necessitated entity is ontologically dependent on the necessitating entity. Those necessary connections are explainable just by what ‘ontological dependence’ means, so if all the necessary connections are of that kind, we’re okay.
If that’s right the argument to priority monism is pretty quick. The truthmaker theorist needs not only truthmakers for atomic truths but also a totality truthmaker that says that all the first-order truthmakers are all the first-order truthmakers. The existence of the higher-order truthmaker necessitates the existence of each of the first-order truthmakers: if it didn’t, it wouldn’t be doing the job it was introduced to do. If that necessary connection is to be explainable, then, the first-order truthmakers must be ontologically dependent on the higher-order truthmaker. The fact that the first-order truthmakers exist must be true in virtue of the existence of the higher-order truthmaker. And so we’re driven to the view that the only fundamental being is the higher-order truthmaker – the totality fact that says how the world as a whole is; other things exist – such as the states of affairs of proper parts of the world being some way – but these will all be ontologically derivative entities, dependent on the totality fact.
I don’t particularly care as to whether one should modus ponens and be a priority monist or modus tollens and reject truthmaker theory. I care about the conditional; any thoughts on it will be welcome.