This is valid:
Every graduate student (A) is highly intelligent (B). Every teacher (C) is a graduate student (A). Therefore, every teacher (C) is highly intelligent (B).
This is invalid:
Every graduate student (A) is highly intelligent (B). Every teacher (C) is highly intelligent (B). Therefore, every teacher (C) is a graduate student (A).
Illogical arguments can take many forms. Confirming the consequent, for example, is illogical, as is denying the antecedent. Some very clear examples of these non-sequitur errors in logic can be found on Stephen Downes' Web, "Guide to the Logical Fallacies". Some of you might want to follow the link to the index for Stephen Downs' guide.
Below is an example of real-time thinking. Is there faulty logic in this example?
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As I was driving home from work one day, I stopped to watch a local Little League baseball game that was being played in a park near my home. As I sat down behind the bench on the first-base line, I asked one of the boys what the score was. "We're behind 14 to nothing," he answered with a smile. "Really," I said. "I have to say you don't look very discouraged." "Discouraged?" the boy asked with a puzzled look on his face. "Why should we be discouraged? We haven't been up to bat yet." |