Last weekend my brother and I were discussing the statement “This statement is false.” Today a colleague mentioned a similar statement, “The following statement is true. The previous statement is false.” Another colleague likened this kind of pure self-contradiction to the Cretan paradox, also known as the Epimenidean paradox: the statement “All Cretans are liars” said by a Cretan, which would seem to be a false if it’s true and true if it’s false.
But the difference between the Cretan paradox and pure self-contradiction is that the Cretan paradox has a real-world referent. It makes a statement about something external to the assertion. Pure self-contradiction has no real-world referent. It makes an assertion about nothing other than itself and thus has no truth value ascertainable.
As it happens, the source of the Cretan paradox is something Epimenides wrote in support of the immortality of Zeus:
They fashioned a tomb for thee, O holy and high one
The Cretans, always liars, evil beasts, idle bellies!
But thou art not dead: thou livest and abidest forever,
For in thee we live and move and have our being.
Epimenides was himself a Cretan. Thus we know through simple pragmatics that he must have been excluding himself without saying so. To treat it as a paradox is to be disingenuous. It’s fun sport, but in the end it just shows one of the things you can’t do in logical reasoning.
Statements such as the Cretan paradox are an illusion caused by conflation of one level of analysis with a higher level of analysis: an evaluation of the members of a set cannot itself be a member of the set evaluated; evaluation is a comparison of something against one or more criteria from an external perspective – what is being analysed is subsumed within its perspective. Once we acknowledge that the statement “All Cretans are liars” cannot be part of the set of statements evaluated (making it thus a simple problem in pragmatics rather than a trick of logic), we identify an unstated assumption that makes it function, without which we get a sort of Escher staircase illusion, something that can’t exist in the real world.
But with mutually evaluative statements such as the pure self-contradictions, each must be on an evaluative level above the other – each must subsume the other within its perspective. And at the same time each has no further reference; it has no claim to truth or falsehood as the set of all other statements by Cretans does (and as that set’s members individually do).
Analyzing an utterance or set of utterances is like weighing an object. In order to weigh an object, you have to lift it (or anyway support it) and you have to be resting on something that is not part of what you are weighing. In the Cretan paradox, we see that the statement that pretends to be part of the set of Cretan statements is actually weighing them and so cannot be part of them; it is evaluating them against their real-world references – that’s what it’s resting on. In the mutual contradiction case we’re looking at, each is weighing the other, and neither rests on anything else, because neither is being evaluated against anything external to itself. It’s like two dudes trying to lift each other simultaneously. In empty space.
Meaning in human communication, ultimately, is not a question first of all of logic; it is a question first of all of pragmatics. All communication is behaviour; when you utter something, you are doing something with the aim of producing a certain effect. The person hearing you will be conjecturing what effect you are trying to produce and responding accordingly. Logic helps serve this function, but pragmatics is the true basis. And the pragmatic value of things such as paradoxes is sport – mental play, fun. And a demonstration of the invalidity of certain kinds of reasoning.