An **antecedent** is the first half of a hypothetical proposition, whenever the if-clause precedes the then-clause. In some contexts the antecedent is called the * protasis*.

Examples:

- If , then .

This is a nonlogical formulation of a hypothetical proposition. In this case, the antecedent is **P**, and the consequent is **Q**. In the implication " implies ", is called the **antecedent** and is called the consequent.^{[2]} Antecedent and consequent are connected via logical connective to form a proposition.

- If is a man, then is mortal.

" is a man" is the antecedent for this proposition while " is mortal" is the consequent of the 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 and "I am the king of France" is the consequent.

Let .

- If then ,.

"" is the antecedent and "" is the consequent of this hypothetical proposition.