Argument by Definition
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A common method of argumentation is to argue that some particular thing belongs to a particular class of things because it fits the definition for that class. For example, someone might argue that a human embryo is a person because it meets the definition of “person.” The goal of this method is to show that the thing in question adequately meets the definition. Definitions are often set within theories. This method is most often used as part of an extended argument. For example, someone might use this method to argue that a human embryo is a person and then use this to argue against stem cell research involving embryos.
This method can be used to argue that something, X, belongs in a class of things based on the fact that X meets the conditions set by the definition. Alternatively, it can be argued that X does not belong in that class of things because X does not meet the conditions set by the definition. The method involves the following basic steps:
Step 1: Present the definition
Step 2: Describe the relevant qualities of X.
Step 3: Show how X meets (or fails to meet) the definition
Step 4: Conclude that X belongs within that class (or does not belong within that class).
To use a basic example, imagine that someone wants to argue against stem cell research involving human embryos. They could begin by presenting a definition of “person” and then show how human embryos meet that definition. This would not resolve the moral issue but she could go on to argue that using persons in such research would be wrong and then conclude that using human embryos would be wrong.
As an example in aesthetics, a person might define a work of horror as a work which has as its goal to produce an emotion that goes beyond fear, namely that of horror, which would be defined in some detail. The person could go on to show how the movie Alien meets this definition and then conclude that Alien is a work of horror.
Since dictionaries conveniently provide a plethora of definitions it is tempting to use them as the basis for an argument from definition. However, such arguments tend to be rather weak in regards to addressing matters of substantive dispute. For example, referring to the dictionary cannot resolve the debate over what it is to be a person. This is because dictionaries just provide the definition that the editors regard as the correct, acceptable, or as the generally used definition. Dictionaries also generally do not back up their definitions with arguments-the definitions are simply provided and not defended.
Obviously dictionaries are very useful in terms of learning the meanings of words. But they are not means by which substantial conceptual disputes can be settled.
When making an argument from definition it is obviously very important to begin with a good definition. In some cases providing such a definition will involve settling a conceptual dispute. Resolving such a dispute involves, in part, showing that your definition of the concept is superior to the competition and that it is at least an adequate definition.
An acceptable definition must be clear, plausible, and internally consistent. It must also either be in correspondence with our intuitions or be supported by arguments that show our intuitions are mistaken. Of course, people differ in their intuitions about meanings so this can be somewhat problematic. When in doubt about whether a definition is intuitively plausible or not, it is preferable to argue in support of the definition. A definition that fails to meet these conditions is defective.
An acceptable definition must avoid being circular, too narrow, too broad or vague. Definitions that fail to avoid these problems are defective.
A circular definition merely restates the term being defined and thus provides no progress in the understanding of the term. For example, defining “goodness” as “the quality of being good” would be circular. As another example, defining “a work of art” as “a product of the fine arts” would also be circular. While these are rather blatant examples of circularity, it can also be more subtle.
A definition that is too narrow is one that excludes things that should be included-it leaves out too much. For example, defining “person” as “a human being” would be too narrow since there might well be non-humans that are persons. As another example, defining “art” as “paintings and sculptures” would be too narrow since there are other things that certainly seem to be art, such as music and movies, which are excluded by this definition. As a final example, defining “stealing” as “taking physical property away from another person” is also too narrow. After all, there seem to be types of theft (such as stealing ideas) that do not involve taking physical property. There are also types of theft that do not involve stealing from a person-one could steal from a non-person. Naturally enough, there can be extensive debate over whether a definition is too narrow or not. For example, a definition of “person” that excludes human fetuses might be regarded as too narrow by someone who is opposed to abortion while a pro-choice person might find such a definition acceptable. Such disputes would need to be resolved by argumentation.
A definition that is too broad is one that includes things that should not be included-it allows for the term to cover too much. For example, defining “stealing” as “taking something you do not legally own” would be too broad. A person fishing in international waters does not legally own the fish but catching them would not be stealing. As another example, defining “art” as “anything that creates or influences the emotions” would be too broad. Hitting someone in the face with a brick would influence his emotions but would not be a work of art. As with definitions that are too narrow there can be significant debate over whether a definition is too broad or not. For example, a definition of “person” that includes apes and whales might be taken by some as too broad. In such cases the conflict would need to be resolved by arguments.
While it might seem odd, a definition can be too broad and too narrow at the same time. For example, defining “gun” as “a projectile weapon” would leave out non-projectile guns (such as laser guns) while allowing non gun projectile weapons (such as crossbows).
Definitions can also be too vague. A vague definition is one that is not precise enough for the task at hand. Not surprisingly, vague definitions will also tend to be too broad since their vagueness will generally allow in too many things that do not really belong. For example, defining “person” as “a being with some kind of mental activity” would be vague and also too broad.
There are a variety of ways to respond to this method. One way is to directly attack the definition used in the argument. This is done by showing how the definition used fails to meet one or more of the standards of a good definition. Obviously, since the argument rests on the definition, then if the definition is defective so too will be the argument.
For example, suppose someone argues that a play is a tragedy based on their definition of tragedy in terms of being a work of art that creates strong emotions. This definition can be attacked on the grounds that it is too broad. After all, a comedy or love story could also create strong emotions but they would not be regarded as works of tragedy.
A second option is to attack X (the thing that is claimed to fit or not fit the definition). This is done by arguing that X does not actually meet the definition. If this can be done, the argument would fail because X would not belong in the claimed category.
As an example, a person might argue that a particular song is a country song, but the response could be an argument showing that the song lacks the alleged qualities. As a second example, someone might claim that dolphins are people, but it could be replied that they lack the qualities needed to be persons.
An argument by definition can also be countered by presenting an alternative definition. This is actually using another argument of the same type against the original. If the new definition is superior, then the old definition should be rejected and hence the argument would presumably fail. The quality of the definitions is compared using the standards above and the initial definition is attacked on the grounds that it is inferior to the counter definition. For example, a person might present a definition of horror that is countered by a better definition. As a second example, a person might present a definition of stealing that is countered by presenting a more adequate definition.