undistributed middle

American  

noun

1. Logic. a middle term of a syllogism that does not refer to its entire class in the major premise or minor premise, with the result that the syllogism is not valid.

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Etymology

Origin of undistributed middle

First recorded in 1820–30

Example Sentences

If the minor were particular, there would be undistributed middle.

From Deductive Logic by Stock, St. George William Joseph

"It will make me simply ill—I could never describe to you," said Miriam, with her face aglow, "what it is to me to hear some silly man drone away with an undistributed middle term."

From Pointed Roofs Pilgrimage, Volume 1 by Richardson, Dorothy Miller

You have committed the fallacy of the undistributed middle term, if you care to know the proper name for it.

From Mr. Isaacs by Crawford, F. Marion (Francis Marion)

If any proposition, therefore, but the first were particular, there would be a particular major, which involves undistributed middle, if the minor be affirmative, as it must be in the first figure.

From Deductive Logic by Stock, St. George William Joseph

Affirmation of the consequent of a disjunctive is equivalent to the same fallacy in the semi-conjunctive form, and therefore involves the ordinary syllogistic fallacy of undistributed middle.

From Deductive Logic by Stock, St. George William Joseph