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

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Example Sentences

See Examples For:

undistributed middle

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 St. George William Joseph Stock

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

From Deductive Logic by St. George William Joseph Stock

The solution to the paradox lies in discovering that the term "population" is used in two different senses, thus exposing the logical fallacy of the undistributed middle.

From Anything You Can Do ... by Randall Garrett

Define and illustrate:—Paralogism, ignoratio elenchi, fallacia accidentis, argumentum ad verecundiam, illicit process, undistributed middle, etc.

From Logic Deductive and Inductive by Carveth Read

But you cannot very well say to an infant of three, "You are now being guilty of an undistributed middle or a petitio elenchi or whatever it is."

From Punch, or the London Charivari, Vol. 158, June 16, 1920 by Various

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