An antecedent is the first half of a hypothetical proposition.

Examples:

• If P, then Q.

This is a standard logical formulation of a hypothetical proposition. In this case, the antecedent is P.

• If X is a man, then X is mortal.

"X is a man" is the antecedent for this proposition.

• If men have walked on the moon, then I am the king of France.

Here, "men have walked on the moon" is the antecedent.