Alias: Arbitrary 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.
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:
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.
Statistical studies of vague concepts require redefinition so that the extension of the concept can be counted, which opens up the way for confusion and deception. Political groups and charities often have an interest in exaggerating the prevalence of some problem so that money can be raised, and political support mobilized, to address it. For this reason, polls and other studies of social problems commissioned by interest groups frequently use low redefinition in order to pump up the numbers. Moreover, the media often play along with interest groups because alarmingly high numbers make for attention-getting stories. So, the next time you hear about such a study, find out whether it was produced by a group with an interest in exaggerating the numbers, and ask yourself whether the numbers reported are plausible. If the numbers are implausibly high, check the report for a low redefinition.
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.