 It’s important to stress that there is no uniquely correct model to be had for any given situation. A model that, for example, interpolated large numbers of intermediaries between Suzy’s throw and her rock’s hitting the bottle would reveal more of the causal structure of both the actual situation and various different counterfactual alternatives. But that doesn’t make it the ‘right’ model for considering the causal status of Billy’s and Suzy’s respective throws with respect to the shattering of the bottle. Such a model would deliver the same result as the simple one described above, and so the additional variables would simply be an unnecessary complication. On the other hand, there are limits on what we can leave out. For example, a causal model that just included ST and BS as variables would not deliver the result that Suzy’s throw caused the bottle to shatter, since that counterfactual is not true on this model. (To get it to come out true, we need to include BH and hold it fixed at its actual value, BH = 0.)