 Let us put truth conditions aside for a while, and ask what it is to believe, or to be more or less certain, that \(B\) if \(A\) — that John cooked the dinner if Mary didn’t, that you will recover if you have the operation, and so forth. How do you make such a judgement? You suppose (assume, hypothesise) that \(A\), and make a hypothetical judgement about \(B\), under the supposition that \(A\), in the light of your other beliefs. Frank Ramsey put it like this: 