Relativism

A man simply lacking the ability to see the laws such as the law of (non)contradiction have their roots in the mere meaning of truth, that from these it follows that talk of a subjective truth that is one thing for one man and the opposite for another, must count as the purest nonsense. He will not bow to the ordinary objection that in setting up his theory he is making a claim to be convincing to others, a claim presupposing that very objectivity of truth which his thesis denies. - Edmund Husserl

In other words: whatever the formulation of the thesis denying the possibility of any objective truth or knowledge, it is inevitably self-contradictory, because in one and the same breath it denies that which it necessarily implies.