The definist fallacy occurs when someone defines a concept in biased terms for the sake of an argument. The person making the argument hopes his or her audience will accept the provided definition, which makes the argument difficult to refute.
The phrase was first coined in 1939 by William Frankena in reference to G. E. Moore’s Naturalistic Fallacy in which Moore claimed that “good” could not be defined in naturalistic terms – terms describing natural qualities of things, such as healthy or pleasurable. Frankena felt Moore was trying to compare apples to oranges by even discussing the definition of good in such terms; Moore had committed the definist fallacy by assuming questionable definitions of both ‘good’ and ‘natural.’
II. Examples of the Definist Fallacy
Example in Politics
A good example of the definist fallacy could be a libertarian defining taxes as “the government stealing from the public.” Though this term is loosely correct in that taxes do entail the government taking money from citizens, it places extreme negative bias on the idea by using the word “stealing” instead of “taking” or “withholding.” This definition makes taxes seem inherently bad. Arguing that taxes are good and necessary would be very difficult if one assumed this definition of the word.
Example in School
Let’s say that your teacher defines using hall passes as “a way to avoid learning.” While this may be technically true, in that using a hall pass can mean you miss out on a lesson for a few minutes, that’s not always the goal of a person using a hall pass. Under this definition, it could be difficult for you to argue that you should receive a hall pass when you need to use the bathroom. When you ask to use the pass, under your teacher’s definition, it looks as if you’re looking to escape the classroom rather than taking care of a need. It would be difficult to argue in your favor if the accepted definition of using a hall pass were “a way to avoid learning.”
III. How to Avoid a Definist Fallacy
To avoid falling victim to a definist fallacy, it is important not to accept definitions, or any statements, uncritically. When someone makes an argument to you, consider whether their definitions could be biased and what difference a less biased, or different, assumption could make to the argument. If you are not knowledgeable about the topic, it may be easier for someone to slip a fallacious definition past you, making it easy for them to convince you of whatever they want you to accept. This technique is often used by advertisers and politicians, and therefore it can be extremely valuable to see past it.
To avoid committing a definist fallacy, try to define terms and ideas factually and without bias. Otherwise, your argument may not appear credible and is certainly open to being shot down, before you have even made your argument.