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

This ghost has recently learnt that it is suffering from an Undistributed Middle, a disease unamenable to treatment, being proof even against the Method of Eloquence, which as you know is a potent specific for most logical defects.

From Project Gutenberg

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 Project Gutenberg

“Ugly Duckling, The,” 25.Undistributed middle, 131.Unity,

From Project Gutenberg

These generally resolve themselves into having more than three terms to the syllogism, either avowedly, or in the covert mode of an undistributed middle term, or an illicit process of one of the two extremes.

From Project Gutenberg

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 Project Gutenberg