Did Wittgenstein think that language-games have presuppositions? He sometimes speaks as if he thought that they do, at other times as though he thought that they do not. For examples, in On Certainty 110, after pointing out that the business of giving grounds for what we say has to come to an end sometime, he remarks, ‘but the end is not an ungrounded presupposition’; whereas, in 115, after warning us that if we try to doubt everything we shall not get as far as doubting anything, he gives as his reason ‘the game of doubting itself presupposes certainty’. It is of some importance for a correct understanding of Wittgenstein to clear up this apparent contradiction.