 A second difference is that an interventionist counterfactual of form “If an intervention were to set \(X=x\), then \(Y= y\)” requires for its truth that all such interventions (or at least all such interventions within the background circumstances in which the causal model of interest is taken to hold) would be followed by \(Y= y\). This has the consequence that, for example, “strong centering” which holds for the Lewis/Stalnaker semantics, does not hold for interventionist counterfactuals. According to strong centering the actual world is more similar to itself than any other possible world. Thus if both \(p\) and \(q\) hold in the actual world, then the “counterfactual” (that is, subjunctive conditional) “if \(p\) were the case, \(q\) would be the case”, is automatically true, As an illustration of the difference this makes, suppose that \(X\) and \(Y\) obey the following intervention–supporting functional relation: If and only if \(X= 1\).5, then \(Y= 3\). Suppose that in the actual world, \(X= 1.5\), \(Y= 3\). Now consider the counterfactual \(C\) : If \(1\lt X \lt 3\), then \(Y=3\). Assuming strong centering, the closest world to the actual world in which the antecedent of \(C\) is true is the actual world in which \(X=1.5\). In this world, \(Y=3\), so \(C\) is true. By contrast, \(C\) is false under an interventionist interpretation, since values of \(X\) between 1 and 3 other than 1.5 are not followed by 3. Arguably the interventionist verdict that \(C\) (and the associated causal claim that “\(X\) being between 1 and 3 causes \(Y=3)\)” are false is the correct view. Several other differences between interventionist counterfactuals and the Lewis/Stalnaker semantics will be noted below.