[M02] Definitions

Lack of clarity in meaning can hinder good reasoning and obstruct effective communication. One way to make meaning clearer is to use definitions. A definition is made up of two parts - a definiendum and a definien. The definiendum is the term that is to be defined, whereas the definien is the group of words or concepts used in the definition that is supposed to have the same meaning as the definiendum. For example, in defining "bachelor" to mean "an unmarried man", the word "bachelor" is the definiendum, and "an unmarried man" is the definien.

We might divide definitions into four kinds. Let us look at them one by one.

§1. Reportive definition

A reportive definition is sometimes also known as a lexical definition. It reports the existing meaning of a term. This includes the "bachelor" example above, or the definition of "prime number" as referring to any integer divisible only by 1 and itself. A reportive definition should capture the correct usage of the term that is defined.

But how do we know what the correct meaning of a term is? Many people think that a dictionary is an authoritative guide to reportive definitions. This is actually a misconception, for various reasons.

First, many words in the language are difficult, if not impossible to define. This includes for example color words which we learn from examples. A dictionary might explain "red" as the color of ripe tomatoes, but obviously this is not what "red" means. "Red" does not mean blue even if all tomatoes suddenly were to become blue when they ripe. Explaining 'red' as 'a certain shade of colour' is of course not enough to distinguish the colour red from other different colours.

Also, the main aim of a general dictionary is often to give enough indication of the main usage of a word so that a speaker can use the word adequately in everyday life. Because of the limitation of space the definitions might not capture adequately the exact meanings of words. For example, the Pocket Oxford Dictionary of Current English defines "religion" as "belief in a superhuman controlling power." Suppose a scientist discovers that there are evil but superhuman aliens on Mars who created us and control our destiny. The scientist would then believe in the existence of a superhuman controlling power. But if this scientist does not worship or submit to these beings, surely this does not mean she has a religion in the usual sense of the term.

Finally, many technical words, such as "microwave", "hyper-inflation", and "a priori" are used in rather specialized ways. The entries in a general language dictionary might not be accurate enough when it comes to such terms. In such cases you should consult a special dictionary for the particular discipline in question.

As an exercise, evaluate the following entries from The Pocket Oxford Dictionary of Current English as reportive definitions.

  • Cat : Small soft-furred four-legged domesticated animal.
  • Magazine : Illustrated periodical publication containing articles, stories, etc.
  • Impress : Affect or influence deeply.
  • Cloud : Visible mass of condensed watery vapour floating high above the ground.
  • Swim : Propel the body through water with limbs, fins, or tail.

What about this entry from the Merriam-Webster Online Dictionary?

  • SUGAR : A sweet crystallizable material that consists wholly or essentially of sucrose, is colorless or white when pure tending to brown when less refined, is obtained commercially from sugarcane or sugar beet and less extensively from sorghum, maples, and palms, and is important as a source of dietary carbohydrate and as a sweetener and preservative of other foods.

§2. Stipulative definition

A stipulative definition is not used to explain the existing meaning of a term. It is used to assign a new meaning to a term, whether or not the term has already got a meaning. If the stipulative definition is accepted, then the term is used in the new way that is prescribed. For example, suppose a stipulative definition is proposed to define "MBA" to mean married but available. Accepting such a definition, we can then go about describing other people as MBAs.

§3. Precising definition

A precising definition might be regarded as a combination of reportive and stipulative definition. The aim of a precising definition is to make the meaning of a term more precise for some purpose. For example, a bus company might want to give discounts to old people. But simply declaring that old people can get discounts will lead to many disputes since it is not clear how old should one be in order to be an old person. So one might define "old person" to mean any person of age 65 or above. This is of course one among many possible definitions of "old".

Or consider a situation where two people are arguing whether animals such as birds or apes possess language. To resolve this dispute, we need to be more precise as to what is meant by "language". If by "language" we refer to any system of communication, then obviously birds and other animals do make use of languages. On the other hand, "language" might be used in a different sense, requiring a combinatorial syntax and semantics, allowing a user of the language to communicate information about non-existent objects or situations remote in time and space from the location of discourse. Used in such a way, the communication system of some animals might not qualify as a language. This example illustrates the use of precising definitions to resolve disputes that involve some key concepts whose meanings might not be clear enough.

§4. Persuasive definition

A persuasive definition is any definition that attaches an emotive, positive or derogatory meaning to a term where it has none. For example, someone against abortion might offer the definition of "abortion" as the murder of an innocent person during pregnancy. This definition carries a negative connotation, as the term "murder" suggests that abortion is wrongful killing, and it also assumes that the aborted fetus is already a person. Such a definition is surely not appropriate in a fair debate on the moral legitimacy of abortion, even though it might be useful as a rhetorical tool.

Evaluate these reportive definitions.

  1. A square is a closed region with four straight sides of equal length.
  2. To tell a lie is to say something that is false.
  3. A gun is any device that shoots a projectile.
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