 So regardless of whether \(\BH_1\in \bW\) or is \(\BH_1\in \bZ\), condition F-G is not satisfied, and \(\BT_0= 1\) is not judged to be an actual cause of \(\BS_2= 1\). The key idea is that it is not enough for Billy’s throw to raise the probability of the bottle shattering; Billy’s throw together with what happens afterwards has to raise the probability of shattering. As things actually happened, Billy’s rock missed the bottle. Billy’s throw together with his rock missing does not raise the probability of shattering.