Any headline which ends in a question mark can be answered by the word no.

If Betteridge was right, then the answer to the headline question should be no, in which case Betteridge was wrong. But Betteridge was wrong, then the answer to the question in the headline is yes.

This isn’t quite like Russell’s paradox. He asked whether the set of sets which contain themselves contains itself. If it does, it doesn’t. If it doesn’t, it does. This logical contradiction led to a more rigorous construction of set theory that avoids the paradox.

Betteridge’s law isn’t a paradox, though it resembles one. If Betteridge was wrong, there’s no contradiction in saying that he was sometimes but not always right.

Betteridge’s law was an aphorism, not a logical absolute, and so was never intended to be a rigorous statement. Betteridge was quite aware that there are exceptions. But as is often the case with yes/no statements that are not always true, it can be turned into a rigorous statement using probability.

Betteridge could have said that if a headline ends in a question mark, the probability that the answer is no is large. Then my headline, added to the vast collection of headlines, would ever-so-slightly lower the proportion of headlines that ask questions that can be answered negatively, without contradicting Betteridge, if was right.