© 2011 by Jensen DG. Mañebog

INFORMAL FALLACIES > Fallacies of Ambiguity

Some forms of invalid arguments originate from the imprecise use of language. An ambiguous word, phrase, or sentence is that which has two or more distinct meanings. Hence, the fallacies of ambiguity all include a confusion of two or more different senses.

Equivocation

This takes place when an ambiguous word or phrase in one of its meanings is used in one of the statements and in another of its meanings in other proposition(s).

e.g. Man is a rational being. No woman is a man. Therefore, no woman is a rational being.

The term “man” is used in two different senses here. The term "man" in the first premise is used as a generic term to include all human beings regardless of gender. In the second premise however, "man" is used in a specific sense as applying only to the male sex.

Amphiboly

An amphiboly occurs when it is the grammatical construction of a sentence that creates the ambiguity.

Example: A candidate for election: I oppose taxes which impede economic development.

Reporter:  The candidate therefore opposes taxes as a whole for they impede economic development.

Because the candidate’s statement is ambiguous, the reporter’s deduction is uncertain. Based on the candidate’s declaration, others will think that he only opposes those taxes that he believes will impede economic development.

Accent

The fallacy of accent emerges when the ambiguity is created by a change in spoken or written emphasis. Thus, for example:

The tutor says John-john is stupid.

Therefore, John-john is stupid according to the tutor.

Depending on the emphasis or pausing to be applied in the sentence, the stupid one referred to is either John-john or the tutor.

Composition

This error in reasoning asserts that the quality possessed by members of a class (or part of a greater whole) is also automatically exhibited by the entire class (or whole).

When I dropped a feather from a 6-story building, it glided to earth very slowly. Therefore, if I will drop this pillow composed of feathers from a 6-story building, it too will float to earth slowly.

What is true to a single feather may not be true to the group of feathers contained within the pillow.

Note that this is different from fallacy of converse accident, which inappropriately generalizes from an atypical particular case (as in "One of the feathers composing the pillow is black; therefore, the pillow is black."). In the fallacy of composition, what we should learn and remember is that even when something can be really said of each individual part, it does not necessarily follow that the same can be truly said of the entire class.

Division

Being the converse of the fallacy of composition, fallacy of division claims that what can be said of the whole can necessarily be said of the parts of the whole.

The American judicial system is a fair system. Therefore, Mike Jimenez will get a fair trial.

The American judicial system is generally and comparatively fair. It has fairness as its attribute. Nevertheless, this does not mean that every trial within that system is automatically fair in itself.

To identify this from the fallacy of accident, it must be remembered that the key point in the fallacy of division is that even when something can be truly said of a whole class, it does not automatically follow that the same can be truly said of each of its single members. (With continuation)