Two interventionist modes of counterfactual evaluation for causal strength

Recent work on interventionist causation has moved beyond the simple cause/non-cause distinction toward comparisons of causal strength. This paper develops an interventionist account of causal strength, grounded in counterfactual evaluation within the framework of structural causal models. I begin by examining Judea Pearl’s counterfactual formalism for causal necessity and sufficiency and argue that it does not, by itself, capture the kinds of general causal comparisons scientists often seek. I then show why Woodward’s notion of counterfactuals is needed for a more comprehensive interventionist analysis. On this basis, I distinguish two modes of counterfactuals and their evaluations. Pearl’s counterfactuals, whose evaluation corresponds to the probability of sufficiency ( \(PS\) ) and the probability of necessity ( \(PN\) ), incorporate factual information and are best suited for singular causal inquiries. By contrast, Woodward’s counterfactuals are defined independently of factual conditioning and support general causal comparisons. I introduce corresponding measures: the probability of interventional sufficiency ( \(PIS\) ) and the probability of interventional necessity ( \(PIN\) ). By clarifying how general and singular strength reasoning are connected, the paper resolves an apparent tension between Woodward’s and Pearl’s approaches and yields a unified interventionist framework for evaluating causal strength in scientific contexts.