Primitive notion: Difference between revisions

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Importing Wikidata short description: "Undefined term motivated informally, usually by an appeal to intuition and everyday experience, or introduced axiomatically and eventually generated only by a series of elementary operations" (Shortdesc helper)
top: suggest to use the first lead sentence for a shorter short-description
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{{short description|Concept that is not defined in terms of previously defined concepts}}
{{short description|Undefined term motivated informally, usually by an appeal to intuition and everyday experience, or introduced axiomatically and eventually generated only by a series of elementary operations}}
In [[mathematics]], [[logic]], [[Philosophy|philosophy]], and [[formal system]]s, a '''primitive notion''' is a concept that is not defined in terms of previously defined concepts. It is often motivated informally, usually by an appeal to [[Intuition (knowledge)|intuition]] and everyday experience. In an [[axiomatic theory]], relations between primitive notions are restricted by [[axiom]]s.<ref>More generally, in a formal system, rules restrict the use of primitive notions. See e.g. [[MU puzzle]] for a non-logical formal system.</ref> Some authors refer to the latter as "defining" primitive notions by one or more axioms, but this can be misleading. Formal theories cannot dispense with primitive notions, under pain of [[infinite regress]] (per the [[regress problem]]).