Let us suppose we are going to insert into Tom’s brain the following false belief: I have an older brother living in Cleveland. Let us suppose the cognitive micro-neurosurgeon can do the requisite rewiring, as much and as delicate as you please. This rewiring will either impair Tom’s basic rationality or not.. Consider the two outcomes. Tom is sitting in a bar and a friend asks, “Do you have any brothers or sisters?” Tom says, “Yes, I have an older brother living in Cleveland.” “What’s his name?” Now what is going to happen? Tom may reply, “Name? Whose name? Oh my gosh, what was I saying? I don’t have an older brother! For a moment, there, it seemed to me that I had an older brother living in Cleveland!” Alternatively, he may say, “I don’t know his name,” and when pressed he will deny all knowledge of this brother and assert things like “I am an only child and have an older brother living in Cleveland.” In neither case has our cognitive micro-neurosurgeon succeeded in wiring in a new belief. In the first case, Tom’s intact rationality wipes out the (lone, unsupported) intruder as soon as it makes an appearance. An evanescent disposition to say, “I have an older brother living in Cleveland” isn’t really a belie —it’s more in the nature of a tic, like a manifestation of Tourette’s syndrome
What this intuition pump shows is that nobody can have just one belief. (You can’t believe a dog has four legs without believing that legs are limbs and four is greater than three, etc.) It shows other things as well, but I won’t pause to enumerate them. Nor will I try to say now how one might use a variation on this very specific thinking tool for other purposes—though you are invited to turn the knobs yourself, to see what you come up with.
Source:
Philosopher Daniel Dennett’s Book Intuition Pumps
