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.

---

Etymology

Origin of undistributed middle

First recorded in 1820–30

Example Sentences

I venture to think that, as in many other cases, the cause of the quarrel is what logicians call an undistributed middle—in other words, that the parties to the dispute have each a different kind of fairy tale in mind.

From Project Gutenberg

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

You old fat fallacy with an undistributed middle—see what you’ve done now!

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