Simple conversion, also called direct conversion, exchanges the two parts of a proposition while preserving truth and quality.
The four rules:
Universal affirmative → particular affirmative.
Universal negative → universal negative.
Particular affirmative → particular affirmative.
Particular negative → no guaranteed converse.
The universal negative is supported by reductio. Particular affirmation rests on shared membership. Universal affirmation requires reduced quantity, while particular negation lacks a generally valid converse.
The next topic is ʿaks al-naqīḍ (conversion by contraposition), another operation involving terms and negation.