A subjunctive conditional $\phi \to \psi$ in which the antecedent is false. The intended evaluation of a counterfactual is generally by reference to the way the world would be were the antecedent to be true. For this reason, the analysis of counterfactual conditionals by means of material implication is generally regarded as incorrect. The truth function of the material conditional is such that a material conditional is true whenever its antecedent is false, but this fails to align with the natural usage of counterfactuals. For example, a counterfactual such as:

• • Had Dubliners not been written by James Joyce, then the sum of 2 and 2 would have equalled 7.

is plausibly regarded as false (or, at least, not true) because Joyce could have decided to only write novels, and nothing about such a choice would suggest that the laws of arithmetic would thereby collapse. The field of conditional logic is motivated by providing a formal analysis of the natural evaluation of how counterfactuals are evaluated.