Quote: can define a class by extension (enumerate its members) or intension (a defining property); can reduce extension to intension

Quotation

A class or collection may be defined in two ways that at first sight seem quite distinct. We may enumerate its members ... Or we may mention a defining property ... The definition which enumerates is called a definition by "extension," and the one which mentions a defining property is called a definition by "intension." Of these two kinds of definition, the one by intension is logically more fundamental. This is shown by two considerations: (1) that the extensional definition can always be reduced to an intensional one [disjunction of each item]; (2) that the intensional one often cannot even theoretically be reduced to the extensional one.   Google-1   Google-2

Published before 1923

Related Topics

Topic: set definition by extension or intension (18 items)