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Single Idea 16484

[filed under theme 4. Formal Logic / C. Predicate Calculus PC / 2. Tools of Predicate Calculus / e. Existential quantifier ∃ ]

Full Idea

Propositions about 'some' arise, in practice, in four ways: as generalisations of disjunctions; when an instance suggests compatibility of terms we thought incompatible; as steps to a generalisation; and in cases of imperfect memory.

Gist of Idea

There are four experiences that lead us to talk of 'some' things

Source

Bertrand Russell (An Inquiry into Meaning and Truth [1940], 5)

Book Ref

Russell,Bertrand: 'An Inquiry into Meaning and Truth' [Penguin 1967], p.83

A Reaction

Modern logicians seem to have no interest in the question Russell is investigating here, but I love his attempt, however vague the result, to connect logic to real experience and thought.

The 4 ideas with the same theme [symbol showing a variable refers to 'at least one' object]:

16484 There are four experiences that lead us to talk of 'some' things [Russell]
13900 'Some Frenchmen are generous' is rendered by (∃x)(Fx→Gx), and not with the conditional → [Lemmon]
13502 ∃y... is read as 'There exists an individual, call it y, such that...', and not 'There exists a y such that...' [Hart,WD]
13523 Existential Generalization (or 'proof by example'): if we can say P(t), then we can say something is P [Wolf,RS]