 In contrast to Carnap, who was at work on modality at about the same time, Reichenbach understands the task of his theory to be to explain the logical form and content of subjunctives, especially of contrary-to-fact conditionals, and, at the same time, to explain how empirical evidence can warrant some counterfactuals, warrant the denial of others, and leave still others undecided. He therefore regards the ability of the theory to account for our common sense judgments of the truth or falsity of sentences involving subjunctives, counterfactuals, laws and modals as critical to its evaluation. 