Retorsion is a philosophical technique used to remind us of the fact that reason (intellect) is always poised toward truth: that it is impossible to think otherwise and that any act – even the act of remaining silent (which is a reaction to understanding terms) – contradicts the skeptical claim that we cannot know anything. To catch an opponent in retorsion is like putting them into a philosophical armbar: it is an act of logical jiu-jitsu.

Retorsion is an important because it helps to support however indirectly our reliance upon first principles, the validity of which cannot be argued for precisely because they are first principles (notice: if first principles – like the principle of non-contradiction – were supported by something more fundamental they would no longer be first). Because of this, retorsion works basically by arguing, “If what you said were true then you could not have said what you said. But, in fact, you did say what you said, in which case what you said cannot be true.” Which itself is to say retorsion arguments (which are reductios) refute a claim by showing that a claim entails a contradiction (mostly by exposing some logical inconsistency in the position itself).

First principles:

Principle of Non-Contradiction – nothing can both be and not be under the same aspect.
Principle of Identity – A is A, and not not-A.
Principle of Excluded Middle – either A or not-A, not neither, not both.

Notice: Just as we cannot think of a square-circle (something that is both a square and not a square under the same aspect), neither could there ever be a square-circle. In other words, a square-circle is not just inconceivable but actually impossible. Because to be is always to be in some way. To assert a contradiction is to say that something is not what it is, and that is a denial of being. Thus, to the extent something exists it is logical. Which is to say the PNC is not only a logical principle (a principle of thought) but an ontological principle (a principle of being).

Using Retorsion to Refute Relativism and Skepticism

Imagine someone utters, “No judgment is objectively true.”

Retorsion reveals the skeptic is contradicting himself because if what he says is true, then at least one judgment is true, in which case what he said is false. Otherwise, what he said is false. Either way, what he said is false, and we can really know that.

If the skeptic tries to revise his claim by saying, “Only this judgment is objectively true,” this must be false as well because no reason could be given for why only that judgment is true, since every judgment which could be advanced in support of that judgment must (because of that judgment) be false. The point? Because there is at least one true judgment this is sufficient to prove that our experience is conformed to what is objectively the case. So, whatever else we can or should be skeptical about, we cannot and should not be skeptical about that.

Now what if the skeptic says, “OK, but that doesn’t mean philosophy can prove anything!” Not so fast. Retorsion can be used here, as well, for if the claim philosophy cannot prove anything is true, then that claim itself cannot be proven. But if the claim that philosophy cannot prove anything is false, then that claim cannot be proven as true. It must be one or the other (not neither, not both) by the demands of logic. From there, we can point out that it has just been proven that the claim “philosophy cannot prove anything” cannot be proven. In which case, philosophy can prove at least something – namely, that the claim “philosophy cannot prove anything” cannot be proven. Which is equivalent to proving that philosophy can prove things.

Really (and to revise the previous metaphor), retorsion helps to expose someone as really having put themselves into a philosophical armbar by having to suppose the very thing they are denying to make sense of – or defend – their claim, which makes their position self-defeating. (If true, then false; and if false, then who cares?)

Let us now consider the Relativist’s claim that “While something may be true for you, it is not necessarily true for everybody.” But again, we ask, “Is that statement true for everybody?” If it is not, then we have no reason to take it seriously, because then it is not truth but opinion — and mere opinion, at that. If it is true for everybody, then it refutes itself because we then have an instance of something that is true for everybody, including those who deny it. Of course, what is true derives from its relation to facts, not from judgments of human beings. If I say there are nine thousand stars in the universe, what makes that judgment true (or false) is whether there really are nine thousand stars in the universe and not what I think or feel about it. Whether there are nine thousand stars in the universe (or not) will be binding truth on all of us, regardless of our current judgment.

Next example,

A similar “retorsive” move can be made in response to Hume’s problem of induction (induction = reasoning from what we have observed to what we have not observed). Hume says we cannot know – or at least we cannot be rationally justified in believing something – unless it is by way of a relation of ideas (necessarily logical relations between ideas, such as bachelors being unmarried) or matters of fact (what has contingently been the case, such as fire producing heat). But since it is conceivable that an effect could exist without its cause in the future (or so Hume claims), the first way is untenable, and to rely on the second approach would be to assume what is under question – namely, that induction is justified; hence, it would be circular. The solution to Hume’s problem of induction? Undermine the undermining. Notice that Hume’s criteria for knowledge fails to meet its own criteria, for there is nothing in the statement, “We can only be rationally justified in a belief because of either relations or ideas or matters of fact,” that is itself justified either by relations of ideas or matters of fact. In other words, if Hume’s criteria were true, then it defeats itself, because there is no way to be rationally justified in believing it, according to Hume’s criteria. But if there is no reason to adopt Hume’s criteria, there is no reason to question the reliability of induction because of Hume’s criteria. How induction works, is, of course, an important question, and there are different accounts on offer1 – for now, it is enough to show Hume’s attempt to undermine induction in fact only undermines itself.

Final example,

Famously, retorsion arguments have been used against certain pre-Socratic philosophers who attempted to deny the reality of change by arguing it would involve something coming from nothing (which is impossible). However, to argue that there is no such thing as change itself requires change – for example, moving from one premise to the next in an act of reasoning – to convince oneself that change is an illusion, which is (you guessed it) an instance change away from our common sense assumption that change is not an illusion. In other words, by attempting to defend the position one winds up refuting it. This does not answer what makes change possible, it only shows that change must be possible, because change is not something that can coherently be denied. One proposed solution is to make a distinction between actual and potential being, as Aristotle did. Either way, the use of retorsion can be enough to show that something is wrong, even if we cannot yet identify (as Aristotle did) why something is wrong.

Conclusion.

What retorsion does is it refutes the more radical forms of skepticism and relativism – shows they cannot be coherently stated without taking on assumptions which disprove the position they are advocating. This is good news. It proves that it is possible to prove things (philosophically or otherwise) and that human beings can really come to knowledge. Of course, a more moderated skepticism may still be tenable – and not only tenable, but preferable. Just because we can know things does not mean we know everything or are not liable to error. Clearly, we make mistakes, and much of our knowledge is provisional. Hence why Mortimer Adler said we should distinguish between those undeniable self-evident truths and knowledge as reasonable affirmation based upon the best available evidence and argumentation, on the one hand, and “mere opinion” formed by contingent happenstance or prejudice and bias, on the other. Most of what we know when using knowledge in the common sense is that middle category – that is, it is not incorrigible and immutable like first principles of thought or mathematic truths – but something we could be wrong about simply because future experience could introduce some new data point that forces us to revise or refine our current understanding of the world. However, there are some things – like those things we’ve examined in this article but others such as the existence of God or the fact that not all swans are white – that we can be certain about, either because of deductive metaphysical reasoning (or here) or because a point of experience has disproved a universal hypothesis (for example, while we could never have been sure that all swans were white, we can now be sure that not all swans are white, after discovering black swans, since it only takes one counterexample to contradict a universal hypothesis).