 The fronting of the presupposition does not lead to a clash with any Gricean principles, so the presuppositions are predicted to project in (16a) and (16b). Similarly, fronting the presupposition that there is a knave to (16a), as in (18a), produces no clash, so (16a) presupposes that there is a knave. But adding the presupposition that there is a knave to (16b), as in (18b), does result in a clash: since (18b) is truth-conditionally equivalent to the simple conjunction “there is a knave and the knave stole the tarts”, it is redundant, conflicting with the requirement of brevity in Grice’s Maxim of Manner. On van der Sandt’s analysis, if fronting a presupposition would produce a redundant result, then that presupposition cannot project. So (16b) is correctly predicted not to presuppose that there is a knave.