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L ogic, philosophy of science Also called counterfactuals or contrary-to-fact conditionals. Propositions expressed in the form: “if P had been the case, then Q would have been the case.” The antecedent is presupposed or known to be false and hence describes a contrary to fact or contrafactual state of affairs. The consequent claims how things would have been were the antecedent state of affairs to be realized. For example, “If I had been the president of the United States at that time, I would not have got involved in the Vietnam War.” All contrafactuals are subjunctive, but not all subjunctive conditionals are counterfactual. The peculiarity of counterfactuals is that they are not truth-functional . Their truth-value cannot be determined by the truth-values of their components. They involve neither material implication nor strict implication . Thus there arises a problem about how to determine the truth conditions of counterfactuals. Currently there are three main positions. One, held by Chisholm , Goodman , and Rescher , suggests that a counterfactual is true if its antecedent P, when conjoined with law-like generalizations and statements of background conditions, will logically entail the consequent Q. The second, held by D. Lewis and Stalnaker , has been developed on the basis of possible world theory and claims that a counterfactual is true if its consequent Q ... log in or subscribe to read full text