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Undistributed Middle
Definition:
Examples:
- All Russians were revolutionists, and all anarchists
were revolutionist, therefore, all anarchists were
Russians.
- The middle term is 'revolutionist'. While both Russians and anarchists
share the common property of being revolutionist, they may be separate
groups of revolutionists, and so we cannot conclude that anarchists are
otherwise the same as Russians in any way. Example from Copi and
Cohen, 208.
- All trespassers are shot, and someone
was shot, therefore, someone was a
trespasser.
- The middle term is
'shot'. While 'someone' and 'trespassers'
may share the property of being shot, it
doesn't follow that the someone in question
was a trespasser; he may have been the
victim of a mugging.
Proof:
Show how each of the two categories identified in the conclusion
could be separate groups even though they share a common
property.
References:
26 May 1995
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