Parks Canada - Teachers' Corner - Memories of War

Memories of War Lesson Plan

Handouts

Good definitions are the basis of rational debate. After all, if we can't agree on what something is, how can we discuss it? The following 6 Rules of Definition are taken from David Kelley's The Art of Reasoning with Symbolic Logic (1990).

i. A definition should include a genus and a differentia .

Good: A dog is an animal with four legs that barks .

Bad: A dog is when…

        A dog is like…

ii. A definition should not be too broad or too narrow.

Broad: A dog is an animal with four legs.

Narrow: A dog is a furry animal with four legs that barks and is named Rex.

iii. A definition should state the concept's essential attributes.

Non-essential: A dog is an animal that is a companion.

A dog is a canine.

Folly is an act that is foolish.

v. A definition should not use negative terms unnecessarily.

A dog is not a cat.

vi. A definition should not use vague, obscure, or metaphorical language.

Maturity is the state of psychological development in which a person becomes well-adjusted.

Death is the cessation of one's participation in finitude.

Life is a cabaret.

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