AUTOPHAGY – RETRIBUTION

A statement can be self-justifying: S. Self-Argued Claim. This self-defense is made possible by the multi-layered semantic structure of language, and in particular by the fact that words have an orientation, that may well be based on implicit arguments, S. Words as arguments.
Just as it can be self-justifying, it can also be self-defeating. A statement is self-defeating when it expresses a logical or material impossibility, or when it involves a pragmatic contradiction between what is said and the act of saying it.

Perelman calls this phenomenon autophagy. defined as a contradiction arising from the fact that “the assertion of a rule or a principle is incompatible with the conditions or with the consequences of its assertion or application. Such arguments can be called autophagy.
Retaliation is the argument that attacks the rule by highlighting the autophagy” (Perelman 1977, pp. 72-73).

The assertion is incompatible with the asserted fact, “the act itself implies what the words deny” (id. p. 73). Perhaps the best-known case of autophagy is that of the Cretan Epimenides claiming that “all the Cretans are liars”:

There are no more cannibals, we have eaten the last one.

S1 — All statements can be questioned.
S2 — I question this statement.

Retribution is a kind of refutation that reconstructs a claim as pragmatically self-defeating on the basis of its own content and principles. In philosophy, this strategy, known as the epitrope, is used by Socrates to refute the thesis of Protagoras according to which:

Man is the measure of all things: of the things that are, that they 
are, and of the things that are not, that they are not. (Plato, Theaetetus, 152a; CW, p. 169)

According to Socrates, this doctrine has the “most exquisite feature” that if it is true, it is false:

Socrates: — Protagoras admits, I presume, that the contrary opinion to his own opinion (namely, that it is false) must be true, since he agrees that all men judge what is.
Theodorus: — Undoubtedly.
Socrates: — And in admitting the truth of the opinion of those who think 
him wrong, he really admits the falsity of his own opinion?
Theodorus: — Yes, inevitably.
 (Id., 171a-b; OC, p. 190)

This refutation is based on the principle of non-contradiction; to maintain consistency, a skeptic must to doubt this principle.

See Prolepsis; Ad hominem; Ex datis.