Fallacies of ambiguity

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These errors occur with ambiguous words or phrases, the meanings of which shift and change in the course of discussion. Such more or less subtle changes can render arguments fallacious.

Equivocation: Using a word in a different way than the author used it in the original premise, or changing definitions halfway through a discussion. When we use the same word or phrase in different senses within one line of argument, we commit the fallacy of equivocation. Consider this example: “Plato says the end of a thing is its perfection; I say that death is the end of life; hence, death is the perfection of life.” Here the word end means “goal” in Plato’s usage, but it means “last event” or “termination” in the author’s second usage. Clearly, the speaker is twisting Plato’s meaning of the word to draw a very different conclusion. Compare with amphiboly, below.

Amphiboly (from the Greek word “indeterminate”): This fallacy is similar to equivocation. Here, the ambiguity results from grammatical construction. A statement may be true according to one interpretation of how each word functions in a sentence and false according to another. When a premise works with an interpretation that is true, but the conclusion uses the secondary “false” interpretation, we have the fallacy of amphiboly on our hands. In the command, “Save soap and waste paper,” the amphibolous use of “waste” results in the problem of determining whether “waste” functions as a verb or as an adjective.

Composition: This fallacy is a result of reasoning from the properties of the parts of the whole to the properties of the whole itself–it is an inductive error. Such an argument might hold that, because every individual part of a large tractor is lightweight, the entire machine also must be lightweight. This fallacy is similar to Hasty Generalization (see above), but it focuses on parts of a single whole rather than using too few examples to create a categorical generalization. Also compare it with Division (see below).

Division: This fallacy is the reverse of composition. It is the misapplication of deductive reasoning. One fallacy of division argues falsely that what is true of the whole must be true of individual parts. Such an argument notes that, “Microtech is a company with great influence in the California legislature. Egbert Smith works at Microtech. He must have great influence in the California legislature.” This is not necessarily true. Egbert might work as a graveyard shift security guard or as the copy-machine repairman at Microtech–positions requiring little interaction with the California legislature. Another fallacy of division attributes the properties of the whole to the individual member of the whole: “Sunsurf is a company that sells environmentally safe products. Susan Jones is a worker at Sunsurf. She must be an environmentally minded individual.” (Perhaps she is motivated by money alone?)

Fallacy of Reification (Also called “Fallacy of Misplaced Concreteness” by Alfred North Whitehead): The fallacy of treating a word or an idea as equivalent to the actual thing represented by that word or idea, or the fallacy of treating an abstraction or process as equivalent to a concrete object or thing. In the first case, we might imagine a reformer trying to eliminate illicit lust by banning all mention of extra-marital affairs or certain sexual acts in publications. The problem is that eliminating the words for these deeds is not the same as eliminating the deeds themselves. In the second case, we might imagine a person or declaring “a war on poverty.” In this case, the fallacy comes from the fact that “war” implies a concrete struggle with another concrete entity which can surrender or be exterminated. “Poverty,” however is an abstraction that cannot surrender or sign peace treaties, cannot be shot or bombed, etc. Reification of the concept merely muddles the issue of what policies to follow and leads to sloppy thinking about the best way to handle a problem. It is closely related to and overlaps with faulty analogy and equivocation.