Take for instance a situation where you’re driving through an underground tunnel and you casually notice that the tenth of a mile digit on the mileage meter turns 6 units. Say this is a tunnel only used to get you to the airport, and so it’s a few months before you drive it again. But eventually, you do need to fly or drop someone off who needs to fly or meet someone who has flown, and so you’re driving down the tunnel once more. This time you notice the tenth of a mile digit moves a mere 4 units by the time the tunnel is behind you. The point of my inserting a 3 month delay in this hypothetical situation is to make it reasonable to assume that recollections about the tunnel’s length are not readily available. Ruling out the lame explanation of mechanical failure on the part of the mileage meter and assuming that in both cases you began and ended your mileage count at the beginning and end of the tunnel, would these incompatible situations necessarily force you to become aware of their incompatible nature and subsequently strike fear in you and make you question the stableness of reality? I don’t know the answer to this question. I do suspect, though, that I’ve experienced incompatible situations. For example, a campus bus stop in Boston moved a couple hundred feet overnight.