The four quantified categorical forms behave differently:
Universal affirmative (A) — converts to a particular affirmative (I).
Universal negative (E) — converts to a universal negative (E).
Particular affirmative (I) — converts to a particular affirmative (I).
Particular negative (O) — has no generally valid converse.
“No guaranteed converse” does not mean every reversed statement must be false. It means truth of the original does not ensure truth of the reversal in every case.
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Simple Conversion: Definition, Categorical Rules and Reductio
The four quantified categorical forms behave differently:
Universal affirmative (A) — converts to a particular affirmative (I).
Universal negative (E) — converts to a universal negative (E).
Particular affirmative (I) — converts to a particular affirmative (I).
Particular negative (O) — has no generally valid converse.
“No guaranteed converse” does not mean every reversed statement must be false. It means truth of the original does not ensure truth of the reversal in every case.