Amphiboly, Fallacy of





This fallacy occurs when a conclusion is drawn from a premise or premises that are ambiguous due to their grammatical structure.  This fallacy has the following form:


Premise:  Grammatically ambiguous premises are presented.

Conclusion:  Claim C is drawn from these premises.


Amphiboly is ambiguity caused by grammatical structure.  Something is ambiguous when it has two or more meanings, and the context does not make it clear which is intended. Some texts refer to amphiboly as syntactical ambiguity (as contrasted with semantic ambiguity). This sort of ambiguity can be used with humorous intent, as in the Groucho Marx line: “one morning I shot an elephant in my pajamas. How he got into my pajamas I’ll never know.”

Ambiguity is not itself a fallacy, but rather a lack of clarity in language (which might be intentional or accidental). The fallacy of amphiboly occurs when an inference is drawn from a premise or premises based on grammatical ambiguity.

While this fallacy is not seen very often, it does have a famous example involving King Croesus of Lydia. This example illustrates how a person can fall prey to the fallacy by drawing the conclusion they favor from premise that is ambiguous.


Defense: As with all fallacies based on ambiguity, the main defense is being aware of the ambiguity. Until the ambiguity of the premises is resolved, the conclusion should be accepted. Even after the ambiguity is resolved, the argument should still be assessed; resolving the ambiguity does not entail that the argument will be good.


Example #1

King Croesus: “Oracle, if I go to war with Cyrus the King of Persia, then what will happen?”

Oracle of Delphi: “If Croesus went to war with Cyrus he would destroy a mighty kingdom.”

King Croesus: “Excellent! After I destroy Cyrus, I shall make many and generous offerings to the gods.”


Croesus ended up destroying his own empire.


Example #2

Roger: “Janet told Sally that she had made an error.”

Ted: “Wow, I’m impressed that Janet was willing to admit the error she made.”


Example #3

Lawyer: “Richard Jones left $20,000 and his cat, Mr. Whiskerpants, to Sally Jones and Daniel Jones.”

Sally: “Looks like I get the money and you get that darn cat.”

Daniel: “What?”

Mr. Whiskerpants: “Meow.”

Originally appeared on A Philosopher’s Blog Read More