Fallacy Friday!

Today's Logical Fallacy is... Half Truth!

(Cherry-Picking, Card Stacking, Incomplete Information, Texas Sharpshooter, suppressed evidence, fallacy of incomplete evidence, argument ...

Friday, June 24, 2016

Today's Logical Fallacy is... Ambiguity!

(amphiboly, semantical ambiguity, type-token ambiguity, vagueness, double meaning)

This fallacy occurs when someone uses imprecise language in their argument in order to mislead the audience. Many languages include words that have multiple meanings, and when these words are used in arguments, we must be clear as to the precise definition of the word that we are using. Ambiguity is often the reason behind failed deductive reasoning. Because ambiguity is inherent to many languages, the mere presence of an ambiguous word or phrase does not automatically make it fallacious. It becomes a fallacy when it is misleading or misrepresenting the truth. This is common with politicians and psychics as a means of protection; the more vague the statement is, the less likely it will come back to hurt you. When we hear an ambiguous statement, we tend to believe the interpretation that we agree with the most.

This fallacy can take several forms including equivocation (using multiple meanings of one word), amphiboly (using grammatical errors often in the form of misplaced modifiers), accent (use of inflection to change the word, often the reason why sarcasm is hard to convey via text), and composition/division (misappropriating characteristics of an individual to a group and vice versa).


“Jorge turned in his assignment on time today” (with the emphasis on today) suggests that Jorge often turns in his assignments late.

“A reckless motorist Thursday struck and injured a student who was jogging through the campus in his pickup truck. Therefore, it is unsafe to jog in your pickup truck. (“In his pickup truck” should have been placed after “motorist.”)

“Really exciting novels are rare. Rare books are expensive. Therefore, really exciting novels are expensive.”

“When the judge asked the defendant why he hadn't paid his parking fines, he said that he shouldn't have to pay them because the sign said 'Fine for parking here' and so he naturally presumed that it would be fine to park there.”

“It is said that we have a good understanding of our universe. Therefore, we know exactly how it began and exactly when.”

“All living beings come from other living beings. Therefore, the first forms of life must have come from a living being. That living being is God.” (“come from” – reproduction first, origin second; “living being” – biological organism first, God second).

“Toyota manufactures dozens of cars.” (Obviously referring to types of cars not numbers – tokens – of cars)

“I did not have sexual relations with that woman, Miss Lewinsky.” (As he later admitted, President Clinton had had "sexual relations" with Miss Lewinsky in the broad sense, and he was denying it only in the narrow sense).

"Last night I caught a prowler in my pajamas.”

“The anthropologists went to a remote area and took photographs of some native women, but they weren't developed.” (from Marilyn vos Savant)

“Don't let worry kill you off - let the Church help.”

“Eight new choir robes are currently needed, due to the addition of several new members and to the deterioration of some older ones.”

“For those of you who have children and don't know it, we have a nursery downstairs.”

“Barbara remains in the hospital and needs blood donors for more transfusions. She is also having trouble sleeping and requests tapes of Pastor Jack's sermons.”

“The Duke yet lives that Henry shall depose.” (Henry VI, Part II; Act 1, Scene 4)

“Be bloody, bold, and resolute; laugh to scorn the power of man, for none of woman born shall harm Macbeth.” (Macbeth; Act 4, Scene 1)

“I am opposed to taxes which slow economic growth.” (What exactly is this political candidate trying to say? Is she opposed to all taxes because they all slow economic growth? Or is she instead only to those taxes that have the effect of slowing economic growth? Some people will see one and some will see the other, depending upon their prejudices and agendas. Thus, we have a case of amphiboly here.)

From Herodotus' histories concerning King Croesus of Lydia: Croesus feared the growing power of the Persian empire and asked many oracles what he should do and if he should march against King Cyrus. The Oracle of Delphi is reported to have answered: that if he led an army against the Persians, he would destroy a great empire. (Considering this to be nice support, Croesus lead his armies into battle, only to lose. If you look closely at the prediction, however, you will notice that it is not made clear which empire would be destroyed, and Herodotus remarks that if Croesus had been smart, he would have sent back a question asking which empire the oracle meant.)

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