Retortion (also spelled 'retorsion') is the philosophical procedure whereby one seeks to establish a thesis by uncovering a performative inconsistency in anyone (any actual or possible rational agent) who attempts to deny it. Let us see if if we can use this procedure to establish the existence of truth, by which I mean the existence of truths. By the existence of truth I mean the existence of truth an sich, in itself, and apart from beings like us. Can it be proven that there are some truths? Can it be proven that there must be some truths?
Performative inconsistency ought to be distinguished from strictly logical inconsistency. The latter is a relation between propositions, which for present purposes we can think of Frege-style as the senses of indexical-free sentences in the indicative mood. Two propositions, p, q, are logically consistent just in case they can both be true, and logically inconsistent just in case they cannot both be true. Performative inconsistency, however, is not a relation between propositions, but one between a mental-linguistic performance, a speech-act or else an episode of unverbalized thinking, and a proposition. Thus the very act of asserting, or of thinking to oneself, that there are no truths 'contradicts' the propositional content asserted or thought, namely, that there are no truths.
There can be logical inconsistency even if there are no thinkers or speakers. All you need for that are two propositions, one the negation of the other, and the other the negation of the one. But there cannot be performative inconsistency unless there are 'performers,' i.e., thinkers and thoughtful language-users. This fact allows for skepticism about the probative reach of retorsive arguments such as the one given above. One can imagine a skeptic giving the following speech:
Your retorsive argument for the ineluctability of truth rests on the contingent fact that there are thinkers and language-users. Thus at the very most it establishes that truth is a transcendental presupposition of thought, discourse, and inquiry. Your argument from performative inconsistency does not establish that truth exists in itself, apart from beings like us. You have not excluded the possibility that truth depends for its existence on beings like us, and is merely something the presupposing of which we find unavoidable. So if the existence of truth is its existence apart from minds, then you have not established that truth exists.
The skeptic is saying in effect that the following propositions are logically consistent:
1. There is no truth in itself apart from us.
2. It is impossible for us to deny that there is truth.
If (1) and (2) are logically consistent, then (2) does not entail the negation of (1). The skeptic's point is that the ineluctability of truth for us, the unavoidability of our presupposing it, has no tendency to show that there must be truths whether or not we exist. If so, then our retorsive thinking above does not reach reality; at best it reaches a transcendental condition of our thinking about reality.
But are (1) and (2) logically consistent? If they are then it is possible that (1). But if it is possible that (1), then it is possibly true that there is no truth in itself. But this is a logical contradiction. For it cannot be possibly true that there is no truth in itself.
So although it seems that a skeptical wedge can be driven between truth-as-transcendental-presupposition and truth as existent in itself, this is a mere appearance. Truth, absolute and existent in itself, is not only undeniable by us, it is undeniable in itself.
Indeed I will go so far as to say that not even God can deny the existence of truth in itself. Suppose God were to assert
1*. There is no truth in itself apart from Me!
Asserting (1*), God is asserting that it is true that there is no truth apart from him. But then there is a truth apart from him, namely, the truth that there is no truth apart from him. The content of the divine assertion 'contradicts' God's asserting of it. So not even God can deny the existence of truth in itself.
If I am told that the divine aseity cannot allow for God's being subject to anything external to him, not even the aboslute truth in itself, then a classical reply would be that God is the absolute truth in itself. In God, truth-as-transcendetal-presupposition and truth as existent in itself are one and the same. God's inability to deny the truth in itself is then his inability to deny himself.
what if the skeptic of truth-in-itself refuses to assert the denial but makes his point as follows:
(A) All truths are relative to a thinker/speaker;
meaning to include (A) in the scope of the quantifier 'all'?
Such a skeptic would avoid the difficulty you raise about the performative inconsistency of asserting the denial of truth-in-itself but achieve the same result (or would he?).
peter
Thanks for the simulating comments.
My concern above is with the existence of truth rather than with the nature of truth. The issues that divide alethic relativists and nonrelativists concern the nature of truth. One can envisage four types of view:
A. Truth is absolute by its very nature, and it exists independently of us (and beings like us).
B. Truth is absolute by its very nature, but it does not exist independently of us.
C. Truth is relative (perhaps along the lines of the relativized relativism you sketch above) and it (therefore)does not exist independently of beings like us.
D. Truth is relative but it exists independently of beings like us.
Now (D) excludes itself 'right off the bat': if it is the nature of truth to be relative, then it cannot exist apart from those to whom it is relative. I reject (C) because I argue that truth by its very nature is nonrelative. But I would concede to you that IF there were a good argument for a form of alethic relativism, then that would be an argument against the existence of truth in itself.
What I am concerned with above is the difference between (A) and (B). Given that truth is absolute, is it also existent in itself or does it exist only when minds like ours exist? Is truth merely a transcendental (and thus unavoidable) presupposition of the thinking, talking, and inquiring of finite minds? Or does truth have a transcendent validity?
Example. It is true that table salt is NaCl. And it would be silly to say that that is true for some people and false for others. (Suppose someone were to say that this true for chemists but not for accordion players.) But if it is intersubjectively true -- true for every actual and possible finite subject -- one might yet wonder whether it is objectively true, true in itself apart from any finite subject.
Suppose there are no finite minds except human minds. Assume that these minds did not exist when dinosaurs roamed the earth. Was it true in the dinisaur days that salt is NaCl? One might say: salt existed back then, but it was not true that Salt is NaCl because truth involves a correspondence between mind and thing, and there were no minds (of the appropriate sort) back then.
Since we disagree about existence I suspect we will disagree about truth as well. These things tend to come as parts of 'package deals.'
Thank you. Are you thinking of Metaphysics, Gamma, 3-4? See Retortion and Non-Contradiction in Aristotle, Metaphysics, Gamma 3, 4 The discssion thread with Rhoda and Michael Sullivan was particularly good.
There are special problems with defending LNC since Graham Priest's counterexamples and arguments kick in. Have you read his work?
For why does a man walk to Megara and not stay at home, when he thinks he ought to be walking there? Why does he not walk early some morning into a well or over a precipice, if one happens to be in his way? Why do we observe him guarding against this, evidently because he does not think that falling in is alike good and not good? Evidently, then, he judges one thing to be better and another worse. And if this is so, he must also judge one thing to be a man and another to be not-a-man, one thing to be sweet and another to be not-sweet. For he does not aim at and judge all things alike, when, thinking it desirable to drink water or to see a man, he proceeds to aim at these things; yet he ought, if the same thing were alike a man and not-a-man. But, as was said, there is no one who does not obviously avoid some things and not others. Therefore, as it seems, all men make unqualified judgements, if not about all things, still about what is better and worse. And if this is not knowledge but opinion, they should be all the more anxious about the truth, as a sick man should be more anxious about his health than one who is healthy; for he who has opinions is, in comparison with the man who knows, not in a healthy state as far as the truth is concerned.
In answer to your other question, no I haven't read Priest, out of distaste, but I suppose I should (distaste being unphilosophical).
I believe I have shown above that truth is undeniable, not just by us, but an sich as the Germans say. But that is quite different from arguing that classical laws such as LNC apply to reality as opposed to being valid only for thought-contents. Aristotle is aware of the gap between laws of thought and laws of reality, but I don't believe he bridges it. I mean: he assumes but doesn't prove that what is true of thoughts is also true of reality.
I believe one must take seriously the challenge represented by Nagarjuna, Heraclitus, Hegel, Nietzsche, and others.
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4. Some undesirables: The skimmers, those who cannot read but only read-in. The sophists who, abusing argument, argue for the sake of argument. The ideologues, those who are out for power, not truth. The uncivil. The illogical. The politically correct. Worst of all, perhaps, are those who exemplify the anti-Socratic property: those who think they know what they don't know. If Socrates was famous for his learned ignorance, these types are marked by their ignorant unlearnededness.