 As noted above, however, this is not to say that the two approaches are identical or always yield identical assessments of particular causal and counterfactual claims. One central difference is that Lewis’ account is reductionist in aspiration—the elements that go into his similarity metric (avoidance of big miracles, perfect match of particular facts etc.) are (at least officially) characterized in non-causal, non-modal terms. By contrast, as explained above, the notion of an intervention and the standards for evaluating counterfactuals to which it gives rise are characterized in causal terms, so that the resulting account is non-reductionist.