中词不周延 Fallacy of the undistributed middle
（重定向自Undistributed middle）
中词不周延（Fallacy of the undistributed middle）是一种形式谬误，是因三段论中的中词在大前提或小前提中不周延，而导致论证无效。
Undistributed middle
中文百科
英语百科
Fallacy of the undistributed middle 中词不周延
（重定向自Undistributed middle）
The fallacy of the undistributed middle is a formal fallacy that is committed when the middle term in a categorical syllogism is not distributed in either the minor premise or the major premise. It is thus a syllogistic fallacy.