Definition of undistributed middle in English:

undistributed middle

noun

Logic
  • A fallacy arising from the failure of the middle term of a syllogism to refer to all the members of a class in at least one premise.

    • ‘In syllogistic logic, failing to distribute the middle term over at least one of the other terms is the fallacy of undistributed middle.’
    • ‘That seems to me to have an undistributed middle.’
    • ‘Or perhaps it was the fallacy called undistributed middle in syllogistic logic.’
    • ‘That's the fallacy of the undistributed middle, or some such.’
    • ‘The undistributed middle is that there are some general grounds of appeal which if they are right may be thought to have certain factual consequences.’