A Formula

Defining something is similar to classifying it. In classifying, we group items together. For instance, we can group sparrows, bluejays, hawks, and so on as types of birds. In defining, we give the features or criteria that allow us to group them together. Using a formula, we may say,


X is (or is not) a Y because it has (or does not have) features A, B, C, and so on

Using words, we might write:


A sparrow is a bird because (1) it is a species of animal and (2) it has feathers.



Here are some examples of definitional claims:


A sick-out is (not) a strike because . . .

Advertisements (music videos, etc.) are (not) works of art because . . .

History is (not) a science because . . .

Single parents (or gay couples, etc.) are (not) families because . . .

TexMex is (not) a language because . . .

Note that the examples above are opinions that others may disagree with. If everyone agrees on a particular definition, such as sparrows being birds, there is no reason to write about it.

When defining some Y, choose examples (Xs) that are on the border between being Y and Not Y, examples that are problematic or controversial. These types of examples make the definition clearer. Also, they may show the need to extend the normal definition to include (or exclude) X within (from) Y. In this way, you create a definition that presents the controversy in a new light.


In determining the criteria, you want to find criteria that are sufficient and necessary. A criterion is necessary if it must be part of the definition. Criteria are sufficient when you have all the necessary criteria together that sets something apart. For example, being a species of animal and having feathers are both necessary and sufficient for defining a bird. The ability to fly, however, is an accidental criterion that is not necessary. For example, ostriches are birds that do not fly.

A few more points

Your paper should focus on an extended definition, that is, a definition somewhat different from standard expectations. In defining your Y term, be sure to establish criteria through claims, evidence, and reasons.

Generally speaking, expect that someone will disagree with your definition. So before matching the X term to the criteria for Y, be sure to argue for the criteria first. If readers agree on the criteria, then it will be easier to persuade them on matching X to Y. In addition, use examples that require some persuasion, not examples that everyone agrees with.

In the introduction, it is important to give some background to why this Y term is problematic and why it is important to define it. That is, why should readers care about this definition? Why should it be important to them? What are its implications?

©2007-2008 Charles Nelson