Philosophers test things. We test arguments for logical validity and soundness. We test propositions for coherence and truth-value. We test concepts and definitions. Testing things is built in to the activity of philosophy. This is the meaning of the famous Socratic ἔλεγχος (elenchos), which is translated as “refutation” or “cross-examination,” but really just means “a careful scrutiny or examination of something.” If that something is a claim, and that claim doesn’t withstand testing, then refutation will be the result, as it typically was with Socrates, since most of his interlocutors’ claims didn’t hold up under testing.
Philosophers have many means of testing claims. One of the best techniques for testing very broad or universal claims or principles is the technique of retortion. It is one of the most useful and one of my personal favorites. ‘Retortion‘ is Latin for ‘turning something back on itself’ (this is what we do when we ‘retort’ to someone—we turn words back on them). In the case of philosophy, retortion means applying a universal principle to itself to test whether it passes its own test or meets its own standard.
Many claims are such that they are self-stultifying, that is, in some critical way or another, they undermine themselves. A self-destructive or self-refuting claim is a claim that, if it is true, must be false, for example “There is no truth”—if this claim were true, it would be false. A self-undermining claim is one that, while it doesn’t itself entail its own falsity, does entail that the claim is unwarranted, and so cannot be known to be true or asserted as true, for example “No human being knows anything to be true”—if this claim were true, we could not know it to be true.
Retortion can also be fruitfully employed in regard to ethical principles and other practical principles or imperatives. As my readers who follow me on Twitter know, I regularly encounter a claim to the effect of “The person who makes a claim has the burden of proof to prove that the claim they are making is true.” Now, this is not a claim I accept at face value, but I always assume the person making the claim actually accepts it (otherwise they are trying to bind me with a rule of argument that they are exempt from, which is clearly unfair, and which I am therefore right to refuse). But if the person making this claim does accept it, it follows—by way of retortion—that he has the burden of proof to prove that the burden of proof does lie with the one who claims, since he is claiming this. And if you follow me on Twitter, you also know that there are all manner of reactions to this—to me, perfectly reasonable—request to obey their own principle, but so far, actually attempting to prove the claim to be true has not been among the reactions. (Of course, it cannot be proven to be true, because it isn’t. They’d do much better if they said “This is a procedural rule I’d like to adopt for this discussion. Would you agree to this?” I wouldn’t agree to it, and would propose an alternative, but this would be the way to go about it.)
Roger Scruton has a rather well-known quote which makes use of retortion to good effect:
There are innumerable principles which at first glance seem to be profound or important insights that go down like wheat before the scythe of retortion:
“No one can know any metaphysical truths, only scientific ones.” How do you know this metaphysical truth?
“Only scientific statements are valid.” That isn’t a scientific statement, so it isn’t valid.
“Everyone’s opinion is equally valid.” Is my opinion that opinions are not equally valid valid?
“We can never be certain of anything.” Are you certain of that?
“No one can have knowledge about God.” How do you know this about God?
“Truth is determined through empirical observation.” What empirical observation determines this to be true?
“What is true for me may not be true for you.” It is true for me that anything true is true for everyone.
“No truth is immutable.” So that truth is mutable, and may have changed.
“No belief can be ultimately justified.” Is that belief ultimately justified?
“It’s always wrong to make moral judgments.” Overheard by philosopher Mary Midgley at a party.
Examples could be multiplied indefinitely, from the lowest banalities of “there is no truth” up to clever and interesting logical paradoxes such as “The set of all sets that do not contain themselves does not contain itself” or “This statement is only false and not true.”
Remember: a very good cognitive habit is to always apply the retortion test to any principle presented to you as absolute or universal. 99 times out of 100, this will burn said principle to the ground. Your interlocutor may get annoyed with you, but that isn’t your fault or your problem. If he is reasonable, he must understand the force of the objection, and seek to reformulate his principle in a rationally cogent manner.