10 Fallacies of Ambiguity
Fallacies of Ambiguity
Ambiguous Language
In addition to the fallacies of relevance and presumption we examined in our previous lessons, there are several patterns of incorrect reasoning that arise from the imprecise use of language. An ambiguousword, phrase, or sentence is one that has two or more distinct meanings. The inferential relationship between the propositions included in a single argument will be sure to hold only if we are careful to employ exactly the same meaning in each of them. The fallacies of ambiguity all involve a confusion of two or more different senses.
Equivocation
An equivocation trades upon the use of an ambiguous word or phrase in one of its meanings in one of the propositions of an argument but also in another of its meanings in a second proposition.
- Really exciting novels are rare.
- But rare books are expensive.
- Therefore, Really exciting novels are expensive.
Here, the word “rare” is used in different ways in the two premises of the argument, so the link they seem to establish between the terms of the conclusion is spurious. In its more subtle occurrences, this fallacy can undermine the reliability of otherwise valid deductive arguments.
Amphiboly
An amphiboly can occur even when every term in an argument is univocal, if the grammatical construction of a sentence creates its own ambiguity.
- 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 this example, the premise (actually heard on a radio broadcast) could be interpreted in different ways, creating the possibility of a fallacious inference to the conclusion.
Accent
The fallacy of accent arises from an ambiguity produced by a shift of spoken or written emphasis. Thus, for example:
- Jorge turned in his assignment on time today.
- Therefore, Jorge usually turns in his assignments late.
Here the premise may be true if read without inflection, but if it is read with heavy stress on the last word seems to imply the truth of the conclusion.
Composition
The fallacy of composition involves an inference from the attribution of some feature to every individual member of a class (or part of a greater whole) to the possession of the same feature by the entire class (or whole).
- Every course I took in college was well-organized.
- Therefore, my college education was well-organized.
Even if the premise is true of each and every component of my curriculum, the whole could have been a chaotic mess, so this reasoning is defective.
Notice that this is distinct from the fallacy of converse accident, which improperly generalizes from an unusual specific case (as in “My philosophy course was well-organized; therefore, college courses are well-organized.”). For the fallacy of composition, the crucial fact is that even when something can be truly said of each and every individual part, it does not follow that the same can be truly said