Contact: Dr. Jan Garrett

This page added/revised November 13, 2002

Concepts should generally be kept distinct in your mind from propositions or statements. The latter are most naturally expressed in complete, declarative sentences, and can be true or false. (In other words, a proposition or statement is the meaning or content of a meaningful declarative sentence.) The premises, intermediate conclusions, and final conclusions of arguments are propositions. For more on propositions, premises, conclusions, and arguments see Positions, Issues, . . . Arguments.

Whereas the natural way in which propositions are expressed is declarative sentences, the natural way in which concepts are expressed is noun or noun phrases (although these are not the only way). For example "person" or "vertebrate animals" or "self-regarding actions" express concepts.

Definitions of concepts do naturally take on propositional or statement form, as will be seen below. Such definitions can be assumptions and operate as premises in logical argumentation. Moreover, in those cases when the concept is a principle or a doctrine, the phrase that expresses that principle will of course take on the form of a statement. For instance, "speciesism is the doctrine that the species of the author has greater moral priority than other species." In spite of these connections between concepts and propositions, most concepts are not propositions but parts of propositions.

A concept is an abstract or general idea generalized from particular instances.

(I took this definition from Webster's New Collegiate Dictionary, 1979.)

Some more examples of phrases that designate concepts:

addictive [substances]
persons with annual incomes in the top ten percent
sentient beings
self-conscious beings
moral agents
morally considerable beings

What is to be done with concepts?

1. If they are key concepts (important to the line of thought of the author), one should keep track of how the terms that designate them are used; the author should not alter the meaning of these terms in the middle of his argument without warning the reader.

2. If the meaning of the concept (or, more accurately, of the term for the concept) is at all in doubt or in danger of shifting in the course of the argument, the author should clarify the meaning by way of a definition. The person who is discussing the argument should make note of this definition and keep track of the role it plays in the discussion. If the author has not clearly defined a key concept, then the reader should try to define it in a way that the author could have or would have accepted. (For example, "The author appears to mean by "person" a rational, self-conscious being and a moral agent.")

A definition can be put into the following basic form:

[term to be defined (TD)] means: [defining phrase (DP)]

for instance

(D) "Person" means a moral agent.

Characteristics of good definitions (partial list):

1. The definition will give necessary conditions:

All TD's are DP.

i.e., DP is a necessary condition for being a TD. "All persons are moral agents" will be true if the sample definition of person just given (D) is a good definition.

2. The definition will give sufficient conditions:

All DP's are TD.

i.e., DP is a sufficient condition for being a TD. "All moral agents are persons" will be true if the sample definition (D) is a good definition.

3. The defining phrase will not be more obscure or ambiguous than the term to be defined.

"A person is a being with a soul" might be criticized under this test if the definition is offered outside any specific, well-articulated theological context where soul has already been carefully defined.