Alias: Arbitrary Redefinition

Taxonomy: Logical Fallacy > Informal Fallacy > Equivocation > Redefinition


In July 1993, the Commonwealth Fund released the results of a telephone survey of 2,500 women, designed and carried out by Louis Harris and Associates. The Commonwealth and Harris investigators took their questions directly from the Gelles and Straus survey…. [T]he Harris/Commonwealth survey concluded that as many as four million women a year were victims of physical assaults…. But the most interesting finding of all, and one entirely overlooked by the press, for it did not harmonize with the notes of alarm in the Harris/Commonwealth press releases, was the response the poll received…about the most severe forms of violence. Gelles and Straus had estimated that these things happen to fewer than 1 percent of women. According to the survey sample, the percentage of women who had these experiences was virtually zero; all respondents answered 'no' to all the questions on severe violence. This finding does not, of course, mean that no one was brutally attacked. But it does suggest that severe violence is relatively rare.

So where did the four million figure for physical assault come from? … Clearly the interpreters of the Harris/Commonwealth poll data were operating with a much wider conception of 'abuse' than Gelles and Straus. Looking at the "survey instrument", we find that they had indeed opened the door wide to the alarmist conclusions they disseminated. … To arrive at the figure of four million for physical abuse, the survey used the simple expedient of ignoring the distinction between minor and severe violent acts, counting all acts of violence as acts of abuse. Five percent of women they spoke to said they had been "pushed, grabbed, shoved, or slapped"; they were all classified as victims of domestic violence and added in to get a projection of four million victims nationwide. … If a couple has a fight, and she stomps out of the room (or yard), and he grabs her arm, this would count as a violent physical assault on her.

…As for jounalists and the newscasters, their interests too often lie in giving a sensational rather than an accurate picture of gender violence, and they tend to credit the advocacy sources. Better four million or five than one or two. … And all the better, too, if the media's readers and viewers get the impression that the inflated figures refer not to slaps, shoves, or pushes but to brutal, terrifying, life-threatening assaults.


Source: Christina Hoff Sommers, Who Stole Feminism? (1994), pp. 196-198.


To redefine a term is, of course, to assign it a new meaning. It is not necessarily fallacious to give a term a new meaning, and it is often done to produce technical terms, but it is a logical boobytrap. There is always a danger of slipping back into using the term in its old meaning out of habit, which could cause a fallacy of equivocation. We may start out reasoning with the term using its new meaning in the premisses, then fall back into using it in its familiar meaning in the conclusion.

There are two types of redefinition, depending on whether the redefined meaning has a wider or narrower extension than the original meaning: Low Redefinition

High and low redefinition are not mutually exclusive categories, as it is possible for a redefinition to be both high and low. This happens when the redefinition applies to some things that the original definition did not, and fails to apply to other things that the original did. For example, if we redefine "bird" as "flying animal", then bats would be "birds" (low), while flightless birds would not (high).

It is even possible for the extension of a redefined term to be disjoint from the extension of the original meaning. This often happens when an existing word is redefined as a technical term. Fortunately, such technical terms are not likely to result in equivocation because the term's two meanings are too different to be confused. Confusion is most likely to occur when the slippage between meanings is subtle.


Subfallacy: The No-True-Scotsman Move



"The No-True-Scotsman Move" is the name given to this version of the fallacy of redefinition by its discoverer, the late philosopher Antony Flew. The name comes from a story that Flew told:

Imagine some aggressively nationalistic Scotsman settled down one Sunday morning with his customary copy of that shock-horror tabloid The News of the World. He reads the story under the headline, "Sidcup Sex Maniac Strikes Again." Our reader is, as he confidently expected, agreeably shocked: "No Scot would do such a thing!" Yet the very next Sunday he finds in that same favorite source a report of the even more scandalous ongoings of Mr. Angus MacSporran in Aberdeen. … "No true Scotsman would do such a thing!" (P. 49)

The No-True-Scotsman Move/Ploy/Fallacy is an unfortunate name since few people are likely to be familiar with Flew's story of the stereotypical Scotsman. However, the name seems to have become firmly attached to it.


This move usually occurs in the course of a debate or argumentation among two or more people. As in the case of the Scotsman, a debater makes a universal claim, such as "all swans are white" or "no swans are black". When an opponent points out that there are black swans in Australia, the debater revises his claims to "all true swans are white" and "no real swans are black". This seems to save the debater's claims from refutation by redefining "swan" to include whiteness and exclude blackness. These are both cases of high redefinition, since the class of swans is narrowed to exclude black swans.

There is a problem with this move that isn't necessarily a problem for high redefinition in general: by excluding black swans from the class of swans, the arguer has made whiteness part of the definition of "swan". The claim that "all swans are white" is an interesting, substantive, but false claim about the world. In contrast, the claim that "all true swans are white" is no more substantive than the claim that "all white swans are white". In other words, the no-true-Scotsman move gains truth at the cost of informativeness. The redefinition that results is true by definition, and therefore tells us only about the arguer's use of the word "swan", rather than about actual swans.

So, the word "true", "real", or "genuine" modifing a common noun such as "Scotsman" or "swan" is a sign of the no-true-Scotsman subfallacy of redefinition. When people talk of "true patriotism", "real democracy", or "genuine Christianity", they may not be speaking of patriotism, democracy, or Christianity.


Acknowledgment: Thanks to Ali Almossawi, Sasha Hettich, and Kevin Fournier for reminding me about this move.

Analysis of the Example:

The Harris/Commonwealth poll was based on a low redefinition of "physical abuse" which produced a large number of cases. "Physical abuse" is a vague concept, and any statistical study of it will have to define it in some precise way in order to be able to count it. Arm-grabbing and pushing may count as "physical abuse" in some situations, so that it makes sense to include questions about them in the poll. However, such a broad definition is a logical boobytrap which could lead to the conclusion that there are more cases of severe violent assaults on women than indicated by the poll.