(a.k.a. Fallacy of the Undistributed Middle Term, Converse Error Fallacy, or Fallacy of the Converse)
A fallacy of form in which the truth of a statement is assumed to assure that a reversed order of the statement is also true
Example:
Five-year-old: If monsters lived under my bed, I would be afraid. I’m afraid. So, monsters live under my bed.
Other things can make a child afraid—like imagination.
Teacher: If molecules turned into people over millions of years, then we would expect we could arrange the various living organisms according to similarity. We can arrange the various living organisms according to similarity. Therefore, molecules turned into people.
We can arrange any group of objects according to similarity, but that doesn’t prove that they evolved from one another. This problem of affirming the consequent is a basic flaw in arguments that claim prediction as a way of proving stories about the distant past.
When a thinker affirms the consequent, the thinker doesn’t distribute the middle term of a categorical syllogism. That’s a fallacy of form, a formal fallacy.
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