LessonsThe Second Figure: Conditions of Validity and Four Productive MoodsQuiz

وضروبه الناتجة أيضا أربعة
This figure, too, has four productive moods.

In each productive mood the major premise is universal. If it tells us only that some major-term instances stand in a certain relation to the middle, those may not be the instances relevant to the minor term. Opposite premise qualities alone are therefore insufficient.

For example:
All cats are animals.
Some trees are not animals.

These premises do not, by form alone, establish the required universal relation between cats and trees. A universal major is required for the standard second-figure inference.

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Why the major premise must be universal

The Second Figure: Conditions of Validity and Four Productive Moods

وضروبه الناتجة أيضا أربعة
This figure, too, has four productive moods.

In each productive mood the major premise is universal. If it tells us only that some major-term instances stand in a certain relation to the middle, those may not be the instances relevant to the minor term. Opposite premise qualities alone are therefore insufficient.

For example:
All cats are animals.
Some trees are not animals.

These premises do not, by form alone, establish the required universal relation between cats and trees. A universal major is required for the standard second-figure inference.