Truth, for so many thinkers throughout history, has been seen as existing independent of human minds. But it seems far more sensible to embrace an anthropological account of truth which Robert Adams nicely describes as the view “that the truths of logic and mathematics are true in virtue of some feature of human thought, which might be ideas in our heads, our intentions regarding our use of language, or proofs we have actually constructed.” (see his book Leibniz: Determinist, Theist, Idealist, p. 182) But this view, while initially plausible, seems to have the following undesirable and counter-intuitive implications that, once understood, may make a commitment to an inhuman ground of truth more attractive: (1) there are no propositions whose truth or falsity we have not yet uncovered or will never uncover; (2) there are true propositions that have no contradictories which threatens the foundations of logic; (3) human communication about the same propositions would seem impossible; (4) truth, rather than our estimations of the truth, would change; (5) there would be no necessary truths, that is, truths that are true in all possible worlds; and (6) the impressive applicability of necessary truths to the physical world becomes unacceptably mysterious. Let me take each in turn.
(1) and (2) can be approached by considering a thought-experiment presented by Bradley and Swartz. Suppose someone is walking alone in the woods and encounters a birch tree which he correctly believes is a birch. Thus, according to the theory that propositions are human creations, we would maintain that the person has a true proposition in his mind or brain, a proposition that doesn’t exist independently of the man and which came into existence with his encounter and consideration of the tree. Now, suppose further that the birch subsequently burns down in a forest fire and no one ever entertains the false proposition that the tree the man encountered was not a birch. This would mean, as Bradley and Swartz point out, “we would have to give up the claim that to every truth there corresponds a non-empty class of falsehoods each of which is a contradictory of that truth. Under this proposal, some truths and some falsehoods would be without contradictories. Not only would this make shambles of logic; it is thoroughly counterintuitive as well. We have a strong disposition to insist that even if no one were to believe of the birch tree that it is not a birch [believing here would be having an affirmative attitude towards the proposition ‘this tree is not a birch’], then were anyone to believe it, what he would believe is false” (see their book Possible Worlds, p. 70). So by agreeing that propositions are not human constructions we can do justice to logic and account for our intuition that there are propositions independent of us whose truth value we don’t know yet or will never know.
(3), that human communication about the same propositions would be impossible, seems to follow if we only share information about propositions that reside in our particular, changing, and unique minds. But if propositions are independent of human minds then perhaps we can think and talk about the same propositions (for example the Pythagorean Theorem). This seems to be required if we are going to have objective truth and avoid the pitfalls of relativism.
(4) In his dialogue On Free Choice of the Will (Macmillan, 1964) St. Augustine wrote: “If truth were equal to our minds, it would be subject to change. Our minds sometimes see more and sometimes less, and because of this we acknowledge that they are mutable. Truth, remaining in itself, does not gain anything when we see it, or lose anything when we do not see it” (p. 67). If so-called true propositions reside in our changing minds then truth would change which is absurd. To be sure, our estimations of the truth change. But not the truth itself.
(5) If all truth is a function of human beings then, since humans are contingent beings that at one time didn’t exist, we would have to accept that truth is as contingent as we are. But this seems unacceptable given the intuition that certain propositions such as 2+2=4 and A=A are necessarily true or true in all possible worlds – even worlds without humans (for some reasons in defense of necessary truths, go here).
(6), the claim that the successful applicability of necessary truths to the physical world becomes unacceptably mysterious, is nicely presented in the form of a question by Bradley and Swartz: “[I]f these necessary truths are merely the result of arbitrary human conventions for the use of mathematical symbols, all this [successful application of necessary truths] becomes a seeming miracle. Why should the world conform so felicitously to the consequences of our linguistic stipulations?” They argue that it is precisely by embracing necessary truths as propositions which are true in all possible worlds, including worlds without humans, that we can provide an adequate explanation of their application in engineering, aeronautics, and so on: “Necessary truths, such as those of mathematics, apply to the world because they are true in all possible worlds; and since the actual world is a possible world it follows that they are true in (i.e., apply to) the actual world” (Possible Worlds, p. 61).
If this cumulative case against the anthropological view of truth succeeds then truth wouldn’t be a human construction. Rather, when we think true propositions we would be contacting entities independent of ourselves. But what would these entities be? Could they be, as Augustine and Leibniz argued, ideas in God’s mind? (For Augustine’s argument here; for Leibniz’s argument go here). Could they be propositions in multiple non-human minds? Might they be abstract entities that exist outside of space and time independent of all minds as some Platonists believe? Or could true propositions be facts or states of affairs as Bertrand Russell once maintained? Are there some other plausible options? What are they?
For a post on the nature of propositions and their relation to the soul, go here.