| | |
| Paragraph 1 |
In the second figure whenever both premisses are problematic, no
syllogism is possible, whether the premisses are affirmative or
negative, universal or particular. |
| Paragraph 2 |
First we must point out that the negative problematic
proposition is
not convertible, e.g. if A may belong to no B, it does not
follow that
B may belong to no A. |
| Paragraph 3 |
Moreover it is not possible to prove the convertibility of these
propositions by a reductio ad absurdum, i.e. by claiming
assent to the
following argument: |
| Paragraph 4 |
This being proved, suppose it possible that A may belong
to no B and
to all C. |
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created 1996/11/25 modified 2009/04/26