 To appreciate the problem, it helps to forget probabilities for a moment and think in simple, folksy terms. Suppose you aren’t sure whether \(A\) is true, but you believe that if it is true, then so is \(B\). If you then learn that \(A\) is in fact true, you then have two options. You might conclude that \(B\) is true, but you might instead decide that you were wrong at the outset to think \(B\) is true if \(A\) is. Faced with the prospect of accepting \(B\), you might find it too implausible to accept, and thus abandon your initial, conditional belief that \(B\) is true if \(A\) is (Harman 1986).