The argument depends upon an ambiguity in grammar, creating a sentence with double meaning. One meaning may make the premisses true, but the conclusion is drawn from the other meaning.



Ambiguous grammatical constructions are fairly common. However, an ambiguous construction by itself is not a fallacy of Amphiboly. It becomes a fallacy of Amphiboly when the wrong conclusion is drawn, i.e. when the ambiguity results in an argument going astray. Be careful not to confuse Amphiboly with Appeal to Humor. Amphiboly can be very humorous, but our laughter is directed at the foolishness of the argument and of the person making the argument. The reasoner is not trying to persuade by means of laughter; rather, we laugh precisely because we see through the argument and are not persuaded by it.



"Headline: Zoo Staff Mothers Abandoned Chimp. The story tells how members of the zoo's staff cared for a baby chimpanzee that had been rejected by its own mother. But what did the mothers of the zoo staff have against that poor baby chimp?" [Based on an actual headline from the Rocky Mountain News.]


"They said they suspect several people of setting the fire. Therefore I can't be under suspicion, since I was alone that night."



Of all the fallacies, Amphiboly is the most fun. The inadvertently clever word play and outrageous misunderstandings to which it gives rise just tickle our sense of humor. Just for fun, here is a sampling--allegedly taken from actual headlines, although I cannot verify that claim--of grammatical ambiguities of the kind that might result in an Amphiboly:

March Planned for Next August

Blind Bishop Appointed to See

Patient at Death's Door--Doctors Pull Him Through

Teacher Strikes Idle Kids

Lawyers Give Poor Free Legal Advice

Juvenile Court to Try Shooting Defendant

Killer Sentenced to Die for Second Time in Ten Years

Autos Killing 110 a Day--Let's Resolve to Do Better

Collegians are Turning to Vegetables

As far as I know, Amphiboly mimics good reasoning in precisely the same way that Equivocation does: if the shift in meaning is subtle enough, it may simply go unnoticed. Frankly, I doubt that this happens very often. Judged by its frequency of occurrence, or its deleterious effect on public discourse, I doubt that Amphiboly is a very important fallacy; but, it is among the oldest of recognized fallacies, and its humor value assures it a place on most lists.


Source: Aristotle, Sophistical Refutations 4 (166a: 5 - 20).


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