Riggs v Palmer has become famous since Dworkin used it to show that legal positivism is defective. The debate over the merits of Dworkin’s claims is still very lively. Yet, not enough attention has been paid to the fact that the meaning of the statute in Riggs was given by the counterfactual intention of the legislature. According to arguments from legislative intent, a judicial decision is justified if it is based on the lawmaker’s intention. But can legislative intentions be determined counterfactually? More generally, what are the discursive commitments undertaken by a lawyer or a judge, in an exchange of legal reasons, when using this interpretive methodology? The paper addresses these issues considering, in particular, David Lewis’s “resemblance” condition and “relevant similarity” between possible worlds in the evaluation of counterfactual statements. The analysis sheds some new light on the debate on theoretical disagreements and shows that Dworkin’s conception of law as an argumentative practice is not necessarily at odds with legal positivism. It rather allows us to look at it under a better light.