Unit 1 · Logic and Proof

1.3Converse, Inverse, and Contrapositive

Quick Answer

Given "If p, then q": Converse: If q, then p. Inverse: If ¬p, then ¬q. Contrapositive: If ¬q, then ¬p. A conditional and its contrapositive are logically equivalent; the converse and inverse are logically equivalent to each other.

Essential Question

How do the converse, inverse, and contrapositive relate to the original conditional, and which pairs are logically equivalent?

Learning Goals

  • 1Write the converse, inverse, and contrapositive of a conditional.
  • 2Determine the truth value of each related conditional.
  • 3Identify logically equivalent statements.
  • 4Write biconditional statements.

Key Vocabulary

Converse

Switches the hypothesis and conclusion: If q, then p.

Inverse

Negates both parts: If ¬p, then ¬q.

Contrapositive

Switches and negates both parts: If ¬q, then ¬p.

Logically equivalent

Two statements that always have the same truth value.

Biconditional

A statement of the form "p if and only if q" (p ↔ q); true when p and q have the same truth value.

Full lesson content coming soon

Worked examples, guided practice problems, a workbook, quiz, and downloadable PDF resources will be added to this lesson in Phase 2. The learning goals and vocabulary above reflect the complete lesson scope.