What are Definitions?

Defining 'Definition' Because the Definition of Terms Matters in Debates

Dictionary. JGI/Jamie Grill/Blend Images/Getty

It may be true that defining key terms and concepts is important to the start of any productive argument, but not all definitions are the same. Most logic texts list five different types of definitions which people might use. This can give the impression that the matter is pretty well settled, but it's not. In fact, the assumption that the matter is settled is part of what gives rise to debates about the nature of definitions every so often.

It might seem strange that a lot of ink and time is spent on something so basic a a "definition," but sometimes it is the most basic of concepts that are the most problematic.


Debating Definitions

Why is discussing the nature of definitions important? If two people involved in a debate are using entirely different types of definitions for the same term, they may only end up talking past each other. This is frequently seen when atheists and theists debate religion or the existence of gods because nearly all the basic concepts are often defined differently by the two groups: atheism, theism, god, religion, etc.

It’s not enough to simply agree on a definition, either, because definitions shouldn't necessarily be accepted at face value. Analyzing the value of a definition can be very helpful because doing so requires understanding what sort of definition you are faced with and whether it’s fulfilling its purpose.


What Is a Definition?

In all cases, a definition is any group of words or symbols designed to explain the meaning of some other word or symbol. Good definitions are those which advance communication and understanding, while bad definitions are those which hinder or at least fail to advance communication or understanding.

Even a bad definition is still a definition, and over the course of debates you may find more bad definitions than good ones.

All definitions are made up of two parts, the definiendum and the definiens. The definiendum is whatever word, symbol, or group of words is being defined; the definiens, then, is whatever words are being used to do the defining. Thus, in the statement "a definition is a group of words or symbols designed to explain the meaning of some other word or symbol," the definiendum is "a definition" and the definiens is everything else.


Definitions and Information

Do definitions convey information? That's a matter of some debate. There are philosophers who argue that because a definition is simply a way of stating that the words in the definiens can be replaced by the words in the definiendum, nothing new is learned. Others, however, argue that because definitions help us clarify and explain ideas, they can therefore help us reveal deeper philosophical truths about the nature of not only language, but our own concepts and thoughts.

What separates a good from a bad definition? That's a difficult question to answer, but a general principle to keep in mind is that it depends a great deal on context — specifically, what the purpose of the definition is.

To answer "is this a good or a bad definition," one must first answer "what are we trying to achieve with this definition?" Thus we must examine the specific situation in which the definition is given and what sort of definition it is supposed to be.

As stated above, most logic texts will describe five different kinds of definitions you may encounter and how to approach them: