Welsh debate

Welsh debater: "I have listened with great care to my opponent's speech this evening and I would like to congratulate him on the impeccable logic of his argument.

Unfortunately the factual premises on which he based his case are quite clearly false.

Now if you combine false premises and faultless logic you must come to a conclusion that is definitely incorrect.

I fully admit that the factual assumptions on which I shall base my argument are just as likely to be wrong as those of my opponent. But I intend to make mistakes in the logic of my argument and so I have at least a random chance of being right.

The probability of my opponent being correct is zero, but I have a small but finite chance of coming to the correct conclusion.

Therefore you must support me on mathematical grounds alone."