Definist Fallacy

Christian Cotton

In war, people are killed. And killing is murder, plain and simple. How anyone can support a war is beyond me.

Anonymous blogger during the George W. Bush administration

We often make use of terms and their concepts in ways that are vague.

The name “definist fallacy” was originally given by philosopher William Frankena (1939) to G.E. Moore’s “naturalistic fallacy,” which Moore char­acterized as the attempt to define general ethical terms, like “good,” in terms of supposedly identical natural terms, like “pleasant.” The definist fallacy consists of (1) defining one concept in terms of another concept with which it is not clearly synonymous, (2) as the persuasive definition fallacy, defining a concept in terms of another concept in an infelicitous way that is favorable to one’s position, or (3) the insistence that a term be defined before it can be used in discussion.

More generally, the definist fallacy is known as “persuasive definition,” a tactic in argumentation that defines a term in an infelicitous a way that is favorable to one’s position, and then insists that the discussion should con­tinue on that basis. Moreover, such definitions are often laden and/or vague, both of which serve to make the position they are used to defend seem more persuasive. Consider, for example, the following exchange on the morality of abortion.

Judith: We’ve come here today to discuss the morality of abortion and the right of a woman to choose what happens in and to her own body. It hardly needs to be said that bodily integrity divorced from per­sonal autonomy makes little sense. For in the absence of bodily integrity, of the right of each person to choose what happens in and to her body, there can be no overt exercise of personal autonomy. Therefore, in securing bodily integrity, it follows that abortion must be understood as a right possessed by women the world over, that it therefore must be a morally permissible practice.

Don: While I agree with Judith that personal autonomy and bodily integ­

rity and the rights that flow from these ought to be respected, I can­not but stand amazed that she would reason that such matters mean that abortion, the practice whereby the fetus, an unborn child - a person - is killed, could be considered not only morally permissible, but a right. For it follows from the fact that a fetus is a person that it, too, possesses the very rights she ascribes to women the world over, viz., personal autonomy and bodily integrity, if not from the womb, then in anticipation of its arrival into the human community. There being no security in those rights where there is not also a right to life - the most basic and fundamental right of all persons - one cannot but conclude that abortion must be morally impermissible.

This interaction may look like the well-reasoned arguments of two sea­soned philosophers, presenting the core disagreement on the morality of abortion. It certainly encapsulates the fundamental principles of the right to choose of the woman and the right to life of the fetus, but Don’s argu­ment falls prey to persuasive definition. Did you catch it? Notice how, in his exposition, he introduces the salient term “fetus” but then goes on to define it, not only as an “unborn child” - a term laden with emotion and connotations of “innocence” and “vulnerability” - but further as a “person” - a distinctly moral concept in which things like innocence and vulnerability are to be defended - who is “killed,” thereby failing to defend those qualities.

Sometimes the definist fallacy refers to a conviction that a term be defined before it can be employed.

can begin about a topic, the term(s) must be clearly defined. The demand for clear definition prior to discussing a topic is not an obvious logical fal­lacy, but it can become so if it’s arrived at by a chain of reasoning: discus­sions are only productive when terms are clearly defined; we want discussions to be productive; thus, we must have clearly defined terms before we begin discussing. Thus, the person who insists in this manner on definition prior to discussion is arguably committing a version of the definist fallacy.

Neal: Welcome back, everybody. I’m sitting here in the studio talking to Uncle Ron about the poor state of the economy and some of the things the folks in Washington can do to get this train wreck back on the tracks. What do you think about taxes?

Ron: Well, Neal, that depends on what you mean by taxation. After all, if we’re going to have anything productive to say about tax policy and how it might help our economy get “back on the tracks,” we should be clear about what we mean.

Neal: Hold on, Uncle Ron. I think you and I, and the members of the listen­ing audience, and I’d dare say even those jokers up in Washington, know what taxation is.

Ron: I’m not so sure, Neal. I bet half of them think taxation is the means by which our Commonwealth is preserved and sustained, while the other half think taxation is the means by which bureaucrats rip off the peo­ple who elected them. So, which is it? [Definitions courtesy of Hurley 2008, 94]

Neal: Why don’t you define taxation for us, then, Ron.

Ron: Legalized theft.

In this exchange, Ron commits a version of the definist fallacy by insisting that discussion wait on a clearly defined notion of taxation. But Neal points out that they and the listeners have an adequate understanding of taxation sufficient to have a discussion on tax policy. It’s surely not a perfect under­standing, but to demand such is to commit this version of the definist fallacy.

The simplest way to not commit any version of this fallacy is to define your terms credibly! Avoid using definitions that are laden with emotion or those that are idiosyncratic. That is, use more neutral and accepted defini­tions. If those definitions seem inadequate for your purposes, then argue for your definition. In other words, give reasons for thinking that a term or concept ought to be defined a certain way. There are even rules for how to test a definition’s strength that can tell you whether your definition is too broad or too narrow, for instance, or even if it’s both too broad and too nar­row. And don’t be hesitant to jump right in without having a clear definition established first (which usually turns out badly anyway). Discussing a topic is one of the best ways to get clearer about what a term means because you have the benefit of other people’s use of the term to provide grist for the mental mill.

Reference

Frankena, William. 1939. “The Naturalistic Fallacy.” Mind 48(192): 464-477.

Hurley, Patrick. 2008. A Concise Introduction to Logic, 10th edition. Belmont, CA: Wadsworth Cengage Learning.