  Wykstra points out that he can accept closure. He can accept, for instance, the implication of closure that S's knowing that she sees a zebra and that being a zebra excludes being a disguised mule entails that S is in a position to know that she is not looking at a cleverly disguised mule while at the same time denying that the very same evidence E whereby S comes to be justified in believing there's a zebra can, by itself, justify – or even boost the probability of – the proposition that it's not a cleverly disguised mule.