Discussing a puzzle about divine simplicity has led us to the metaphysics of truthmaking; I'll just focus on the latter for now - but the broader dialectic is this: I was thinking that a particular view about truthmaking can help us with that puzzle about simplicity. [Cf. first related article below.]
Take your sentence 'Al is fat', and suppose it's true. I agree it must be somehow *made* true, and I agree it can't be made true by Al, or fatness, or the sum or set of the two.
I suspect that we disagree about the following question: Must the sentence be made true by an item (entity, etc.)? If we answer "yes", then the natural proposal is to posit an entity with, as you say, a proposition-like structure, such as a state of affairs of Al's being fat. But suppose we answer "no": though 'Al is fat' must, if true, be made true, it needn't be made true by an item. How could it be made true without being made true by an item? Well suppose we express its being made true as follows:
(*) The sentence 'Al is fat' is true because Al is fat.
That is, the sentence (a linguistic item) is true because Al (a man) is fat. The sentence to the right of 'because' in (*) expresses what it is about the world in virtue of which the sentence 'Al is fat' is true. But (*) nowhere refers to an *item* of Al's being fat. The only referring term appearing to the right of 'because' is 'Al'.
Dan grants that some truthbearers need truthmakers, but thinks that truthmakers needn't be entities. Right here I must lodge an objection. A truthmaker is an entity by definition. That truthmakers are entities is built into the theory. If the true sentence 'Al is fat' (or the proposition expressed by a thoughtful utterance of this sentence) needs a truthmaker, then this sentence/proposition cannot just be true: there must be, external to the sentence/proposition, an entity that 'makes' it true. But of course this entity cannot itself be a truthbearer, whether a declarative sentence, a Fregean proposition, an Aristotelian proposition, a judgment, a statement, a belief, or any cognate item. This point is crucial, so forgive me for belaboring it a bit.
Suppose we have a valid deductive argument all of the premises of which are true. Then, from Logic 101, we know that the conclusion must also be true. To put it precisely, and taking care not to confuse the necessitas consequentiae with the necessitas consequentiis: Necessarily, if the premises are all true, then the conclusion is true. In this precise sense the truth of the premises necessitates the truth of the conclusion.
Could one say that the conjunction of the premises 'makes true' the conclusion, that the conjunction of premises is the truthmaker of the conclusion? One could say this, but this is not what truthmaker theorists mean when that say that a truthmaker makes true a truthbearer, or that a truthbearer needs a truthmaker. What they mean is that some if not all truthbearers need truthmakers that are not truthbearers.
As I use 'truthmaker,' no truthmaker is a truthbearer. (I ignore some recherché counterexamples.) So the proposition Tom is tall is not the truthmaker of the proposition Someone is tall. And this despite the fact that the first proposition entails the second. Does the second proposition have a truthmaker? Yes. In fact it has more than one. Tom's being tall is one, Bill's being tall is another. But these are not propositions, but ontological grounds of true propositions.
So if 'Al is fat' has a truthmaker, then there exists an entity external to this sentence and to every sentence (proposition, etc.) that makes the sentence (proposition, etc.) true. If entailment is a logical relation, then truthmaking is not a logical relation. Logical relations connect propositions to propositions; truthmaking, however, connects a non-propositional chunk of external reality to a proposition (or cognate item). Al's being fat, for example, is not a proposition. It is a state of affairs or concrete fact. Propositions are either true or false, but it is neither; it either exists or it does not. If it exists, then it it can serve as the truthmaker of 'Al is fat.' Concrete (Armstrongian) states of affairs are not bipolar or bivalent items. In this respect they are not like Chisholmian-Plantingian abstract states of affairs.
What Dan should say is there is no need for truthmakers, not that truthmakers needn't be entities.
(*) The sentence 'Al is fat' is true because Al is fat
to show that a truthmaker need not be an entity.
It seems to me, though, that Dan is confusing a truthmaker with a truth condition. A truthmaker is concrete chunk of extralinguistic and extramental reality whereas a truth condition is just another sentence, proposition, or cognate item. Our old friend Alan Rhoda in an old blog post does a good job of explaining the distinction:
. . .truthmakers are parcels of reality . . . .
Not so with truth conditions. Truth conditions are semantic explications of the meaning of statements. They tell us in very precise terms what has to be true for a particular statement to be true. For example, a B-theorist like Nathan Oaklander will say that the truth conditions of the sentence "The 2006 Winter Olympics are over" is given by the sentence "The 2006 Winter Olympics end earlier than the date of this utterance". Thus truth conditions are meaning entities like statements that are used to spell out or analyze the meaning of other statements.
Dan's (*) merely sets forth a truth condition. It doesn't get us off the level of propositions and down to the level of truthmakers.
Another important point has to do with the asymmetry of truthmaking: if T makes true p, it does not follow that p makes true T. It's an asymmetry of explanation. If one thing explains another, it does not follow that the other explains the one. The truthmaker theorist takes seriously the project of metaphysical explanation. Truthmakers explain why true truthbearers are true. Dan's (*), however, entails the following non-explanatory biconditional:
(**) The sentence 'Al is fat' is true iff Al is fat.
But (**) has nothing to do with truthmaking; it is but an instance of Quine's disquotational schema according to which the truth predicate is but a device of disquotation. We remain on the level of sentences (propositions, etc.)
In sum, I see no merit in Dan's suggestion that there are truthmakers but they needn't be entities. That shows a failure to grasp the notion of a truthmaker. What Dan should say is that there is no need for truthmakers. He might also try arguing that the truthmaking relation is bogus or unintelligible since it is neither a logical relation nor a causal one.