 Suppose, by contrast, we require that interventions be “possible” in some more demanding sense (that is, we adopt a notion of possibility constrained intervention) and we consider counterfactuals of the form: “if an intervention meeting  M1–M4  were to occur that sets the gravitational attraction of the moon to a different value, then…”. It may well be that there is no physically possible process that will meet the conditions  M1–M4  for intervention on the moon’s position with respect to the tides—all possible processes that would alter the gravitational force exerted by the moon may be insufficiently “surgical”. For example, it may very well be that any possible process that alters the position of the moon by altering the position of some other massive object will have an independent impact on the tides in violation of condition  (M2)  for an intervention. Woodward (2003) argues that nonetheless we have a principled basis in Newtonian mechanics and gravitational theory themselves for answering questions about what would happen if such a surgical intervention were to occur and that this is enough to vindicate the causal claim  (G).  On this view of the matter, what is crucial is not whether the antecedent of the relevant counterfactual is nomologically or physically possible but rather whether we are in possession of well-grounded scientific theories and accompanying mathematics that allow us to reliably answer questions about what would happen under the supposition of such antecedents. We count interventions as “possible” as long as this is the case. Such interventions should be distinguished from interventions that are logically, conceptually or mathematically inconsistent or incoherent (see below for additional illustrations). 