(2) The quality of the converse must be the same as that of the convertend.
§ 483. The first of these rules is founded on the nature of things. A violation of it involves the fallacy of arguing from part of a term to the whole.
§ 484. The second rule is merely a conventional one. We may make a valid inference in defiance of it: but such an inference will be seen presently to involve something more than mere conversion.
§ 485. There are two kinds of conversion—
(1) Simple.
(2) Per Accidens or by Limitation.
§ 486. We are said to have simply converted a proposition when the quantity remains the same as before.
§ 487. We are said to have converted a proposition per accidens, or by limitation, when the rules for the distribution of terms necessitate a reduction in the original quantity of the proposition.
§ 488.
A can only be converted per accidens.