The second route uses one affirmative and one negative premise, with at least one universal. The negative premise ordinarily contributes an exclusion relation.
But spotting opposite qualities and a universal is not enough by itself to license any desired conclusion. One must identify the relevant instances and check the direction of the two terms in the proposed conclusion.
This distinction prevents a syntactically similar but invalid argument from being taken as a productive mood.
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The Fourth Figure: Productive Conditions, Moods and Proofs
The second route uses one affirmative and one negative premise, with at least one universal. The negative premise ordinarily contributes an exclusion relation.
But spotting opposite qualities and a universal is not enough by itself to license any desired conclusion. One must identify the relevant instances and check the direction of the two terms in the proposed conclusion.
This distinction prevents a syntactically similar but invalid argument from being taken as a productive mood.