contrafactual

Contrafactual is an adjective relating to counterfactual statements or propositions—claims about what would be the case if past events or circumstances had differed. In common usage, contrafactual reasoning contrasts with statements about what actually happened, and it is often used to describe hypothetical scenarios that diverge from history.

In philosophy and logic, contrafactuals are conditional sentences whose antecedent did not occur in fact. A standard form is: If A had occurred, B would have happened. The study of their truth conditions has employed possible-worlds semantics, notably developed by Lewis and Stalnaker. Under this approach a contrafactual is true if, in the closest possible world where A is true, B is true; if no such world exists, the statement may be false or undefined. Subjunctive mood and causal reasoning are closely linked to these analyses.

In causal analysis and history, contrafactual reasoning is used to infer causes and assess what would have happened under different conditions, such as evaluating the effects of a policy by imagining alternative histories. Causal inference often formalizes contrafactuals in counterfactual models and simulations despite the limitation that such scenarios are hypothetical.

In psychology, contrafactual thinking involves imagining alternative outcomes to events, which can influence emotions and decision making. Upward contrafactuals (imagining better outcomes) can provoke regret, while downward contrafactuals (worse outcomes) can provide relief. The tendency varies with personality, memory, and context.

Contrafactual is frequently treated as a variant spelling of counterfactual; many fields use the more common term counterfactual. Related concepts include counterfactual conditional, possible worlds, and subjunctive mood.