3. The Undistributed Middle Term

In our discussion of syllogistic argument, we saw that the middle term (the term appearing in the premises but not in the conclusion) must be a universal term (distributed) at least once in order for it to have the proper scope to make the connection between the major term and the minor term. If this fails to happen, we have the formal fallacy called the “undistributed middle term.” A less technical name given to this fallacy is “guilt by association.” We can see the pertinence of the latter name in this example:

 

Several Nazis were members of the Kaiser Club.

Hans was a member of the Kaiser Club.

Therefore, Hans was a Nazi.

 

COMMENT: This is fallacious reasoning because, contrary to what the conclusion asserts, it does not follow that just because Hans belonged to a club that had Nazi members he was himself a Nazi. This circumstance might raise certain suspicions about Hans, but it does not allow us to proclaim as a fact what can be at best only conjecture.