Sorting Through Sophistries
The Ambiguous Fallacies

By Gabriel Blanchard

Language is a tool, and, like all tools, neutral; it will serve a sophist as faithfully as yourself.

In our first post of this series, we established what fallacies are, and explained that in this series we are dealing with informal fallacies only. We may now proceed to discussing the various kinds of informal fallacy.

How Many Sophistries Are There?

There are a few large subgroups—genera within the family of informal fallacies, so to speak, each with its own collection of species. These genera can be determined in various ways: according to which of the rhetorical topics* they parody, for example, or according to the quality that seems to give them plausibility. Aristotle listed a total of thirteen, six of lexis [λέξις] (conventionally translated “diction” or “wording”) and seven others (which, he argues, are really one genus and six species of that genus). We don’t propose to attempt a complete taxonomy here and now. That task may not even be possible, and it is certainly beyond both the needs of this series and the powers of the present author! But we may begin with the deceitful subcategory of fallacies of lexis, fallacies based in language itself.

Lexica Fallacia

In the last post, we said that informal fallacies are often deliberate, so it’s important to note that these can be mere misunderstandings. But even unintentional fallacies are fallacious nonetheless; and of course, there are bad-faith reasoners who will try to use them to their advantage.

Working from Aristotle’s outline, we can identify three distinct species of the genus “fallacies of lexis“: the ambiguous species (the philosopher lists two subspecies, equivocation and accent); the pseudo-subalternating** species (again with two subspecies, composition and division); and the metaphoric species. Let us begin with that first species and its variants.†

Ambiguity, or vagueness, takes advantage of key terms whose meanings have not been adequately clarified. This depends somewhat on context, of course. Few of us aspire to be W. T. Kirkpatrick, whose most famous student relates an episode in which he unintentionally ruined a game of bridge his wife had planned: he could still be found in the drawing room an hour later, begging the assembled Edwardian ladies to define their terms.‡ But, in the context of a more premeditated debate or discussion, ideally, key terms should be clearly defined at the outset.

Humans are not pigs; they'll eat anything.


There are (ironically) several specific forms ambiguity can take. One recognized by Aristotle is equivocation. This relies on moving back and forth between two unrelated senses of a word, or two words that are homonyms in sound or spelling. Anna Julia Cooper, during the intense social conflicts following Reconstruction, gave an amusing example in her book A Voice From the South:

Light is opposed to darkness.
Feathers are light.
Ergo, Feathers are opposed to darkness.

The equivocal term here is, of course, “light”: in the first premise it means illumination, brightness, while in the second it means insubstantial, the opposite of “heavy.” This is a fairly simple instance of equivocation, more or less amounting to a malicious pun. There are subtler instances; in fact, some highly sophisticated disputes in theology and philosophy deal with whether certain claims can be univocally true (the word is the same because the idea is the same) or analogically true (the word is the same because two distinct ideas are similar in some way), or are only equivocations.

Fallacious Prosody

Aristotle also mentions a lexic fallacy of accent, or of prosody (as the relevant term [προσῳδία] is also translated). The fallacy of accent resembles equivocation, and highfeathers§ a closely related but distinct problem: the role that pronunciation, especially stress, can play in determining meaning. For instance, the plain assertion “I’m not a paid informant” may be enough to settle the mind of the mafia don one needs to mollify (we’ve all been there)—unless one says it “I’m not a paid informant,” which suggests that the negation applies only to the accented part of the statement.

Mottes, Baileys, and Goalposts

Other forms of ambiguity also exist, some of which seem not to be known to Aristotle, or at any rate did not earn the dignity of a dedicated heading. Another closely-related pair are moving the goalposts and the motte-and-bailey fallacy. The latter is named for an early medieval type of fortification: a small, easily defensible stronghold (e.g. a sturdy stone tower atop a hill)—the motte—is surrounded by a pleasant stretch of land with a very light defensive perimeter—the bailey. The land of the bailey is what the residents actually want, but is difficult to defend; when attacked, residents retreat to the motte, which may be cramped and dreary but is as defensible as you could ask for. In argument, a motte-and-bailey involves implying a highly controversial or hard-to-prove position, but, when challenged, saying something like “All I meant was …” and following up with a claim that seems similar but is far easier to maintain. (Nicholas Shackel, who coined the name motte-and-bailey for this fallacy, used it to critique postmodernist claims like “morality is socially constructed.” He considered the bailey of this to be “there is no such thing as right and wrong,” and the impregnable motte “our beliefs about morals are influenced by our society”; however, on this subject, take note of the warning in the last segment of this post.)

Moving the goalposts typically operates in much the same fashion, but reversed: more exacting requirements than were initially asked are introduced later on in order to justify rejecting an idea, or as the price of accepting it.

Fallacy—or Error?

In addressing these two forms of ambiguity, we must add a word of caution. The reason fallacies of ambiguity exist at all is that we do not always understand things perfectly the first time we hear or read them. It is possible to just misunderstand someone; it is, therefore, possible accordingly to think they’re retreating to a motte when they considered it their bailey the whole time, or to feel the goalposts have been moved when in truth it was an illusion that they looked so close at first. Shackel, mentioned above for his critique of postmodernist thought, was in turn critiqued by Randy Harris, a professor of rhetoric at Ontario’s Waterloo University: Harris did not say that the phenomenon Shackel had described did not exist, but rather that the postmodernist authors he attacked were not in truth guilty of it, and that Shackel himself had thus fallen short of the rules of courtesy which debate demands.

In all cases of ambiguity, the solution is: be as clear as you know how to be. Ideally, do so right from the start—but if you realize you’ve made a mistake, the only things to do are the three F’s: ‘fess up; fix it, as best you can; and resume moving forward.

*The rhetorical topics are the base kinds of argument on which syllogisms themselves are constructed. Four are traditionally recognized: definition; analogy; cause and effect; and authority.
**This name comes from the logical process of subalternation. Subalternations are deductions that can be drawn from, or about, the particular propositions on the square of opposition. For example, if the particular proposition “some cabbages are in this soup” is true, then the universal proposition “no cabbages are in this soup” must be false; or, if “all cabbages are in this soup” is true, then “some cabbages are in this soup” must be true as well. These are valid subalternations. The pseudo-subalternate fallacies superficially resemble these, but really say something else.
†And in this trinity none is afore, or after other; none is greater, or less than another; but the whole three fallacies are co-fallacious together, and co-equal. So that in all things, this unity in fallacy and trinity in unity is to be rejected.
‡This story, and the said famous student’s general view of the gentleman in question, can be found in C. S. Lewis’s Surprised by Joy (specifically in Chapter IX, “The Great Knock”).
§Feathers are light (which I have on the authority of no less than Anna Julia Cooper, and she had a degree from the Sorbonne), so I assume this replacement is perfectly straightforward and acceptable.


Gabriel Blanchard is CLT’s editor at large. He lives in Baltimore, MD.

If you enjoyed this piece, please write an essay explaining the difference between “enjoy [frui]” and “enjoy [delectari]”; but if you’d rather not do that right now, take a look at our introductions to authors like Christine de Pizan and Robert Boyle, or to ideas like mystical wisdom and how to categorize fields of study.

Published on 18th January, 2024.

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