Famous example: consider someone who hasn't noticed the Blair -> Brown transition. S/he believes that the prime minister's surname begins with B, and is correct, and even has something like a justification ("I remember seeing the announcement of the prime minister's election, and the name began with B, and I haven't seen any change of power since then").

(The original form of this objection, or at least the earliest one I've seen, involves a different pair of prime ministers whose names begin with B. Balfour and (Campbell-)Bannerman, perhaps.)

Though of course that's precisely an example of something else.

Well, kinda, but actually I think it's very similar. In each case, you have something that looks like a justification and has the right sort of general form to be one, but isn't really. The only difference is that Simon noticed and Bannermanman didn't.

Er oops, that was me.