The most basic thing we can ask about anything is “What is it?” Young children explicitly ask this question all the time. But even adults do it, although they may not do it explicitly, or even think about doing it at all. We ask this about words we don’t know, and things we encounter for the first time. We even engage in definition when we write a mission statement for an organization—or for ourselves. It is something that all of us do, and yet few of us can explain the right way to do it.
When we think about “definition,” we can be thinking about one of two kinds: nominal definitions and real definitions.
A nominal definition expresses the meaning of a term by indicating what it refers to. It “points to” the thing it signifies: What is a bird? A bird is all of the ducks and geese and chickens and pelicans and storks and ostriches and horn bills, etc. that ever were, are, or will be flying or walking around in the world. This is a kind of nominal definition called connotative definition.
Etymological definitions are another kind of nominal definition. If I want a definition of the word “philosophy,” for example, I could simply point out that the word is made up of two Greek words—philia and sophia, “love” and “wisdom.” Etymologically (in other words, according to the derivative meaning of the word’s elements), the word “philosophy” means “the love of wisdom.”
But nominal definition, whether connotative or etymological, doesn’t really get to the underlying nature of the word or thing it attempts to define. We need another kind of definition for this purpose. Although nominal definitions are important, real definitions are more important. Nominal definitions are important because they identify the object of the definition. Many times it is helpful to know what a term refers to before we can state its nature, and what we are essentially doing when we use nominal definitions is naming things (from nomen, nominis: “to name”).
While nominal definition approaches the question of what a thing is in an extrinsic way—from the outside, so to speak—real definition tries to get to the intrinsic or inner meaning of a thing. It attempts to express something’s inner meaning. In the act of real definition we lay bare the nature of the object we are defining.
According to Aristotle and many of the great ancient and Medieval philosophers, the best way to define the nature of the thing is to ask four basic questions about the thing you are trying to define. These are called the “four causes.”
- Formal Cause
- Material Cause
- Efficient Cause
- Final Cause
Let’s talk about what these four causes are and then give a couple of examples so we can see how they manifest themselves.
Formal Cause: We say that formal cause involves asking what kind of thing something is. The formal cause, in other words, determines the form or shape of a thing. Let us now reconsider our original question. The formal cause of a thing is that thing’s nature or essence, the metaphysical pattern of a thing. It is that element of a thing that determines most fundamentally what it is.
Material Cause: The physical stuff of which a thing is made up we call “matter.” Now, we said that the formal cause of a thing is determinate. This means that a thing’s form or shape is determined by its formal cause. But what is it that the formal cause determines? What is it that is shaped into the thing that we apprehend? The answer is: matter. Matter is the underlying physical substratum of things, and it changes from one form to another depending on which formal cause is determining or shaping the matter.
Efficient Cause: The efficient cause is the external agent that brings about this unity between material and formal cause, or that which sustains it in existence.
Final Cause: The fourth and last cause is related to why the agent brings the thing about in the first place. There must be a reason, or purpose, for the unity of form and matter that is brought about by the efficient cause. This reason or purpose for a thing is what we call its final cause. The final cause is the purpose or end served by the thing, and that for which it exists. It is what a thing is for.
We could summarize the four causes—formal, material, efficient, and final—by saying that they constitute the wherefore, the wherewith, the whence, and the why, respectively. They answer all the fundamental questions involved in fully saying what a thing is.
Consider a few examples.
If we consider a house, we would say that the plan or blueprint for the house is its formal cause; the materials used to build it (wood, nails, steel reinforcement) are the material cause; the architect and the builder are the efficient cause; and the purpose of the building (for a dwelling, for office space, for worship) is the final cause.
My mother used to sew dresses for my sister. She would go to the store and buy a pattern (formal cause) and some cloth (material cause), and then she herself (efficient cause) would cut the cloth according to the pattern in order to provide clothing for my sister (final cause).
We could even ask, “What are the four causes of the world?” For which the answer is to simply look at Genesis, which is all about God (efficient cause) forming and filling the world (formal and material causation) in order to bring about the world—a world in which dwells a being made in His image and likeness (final cause).
With these four questions we can define the world and everything in it.