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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 15 ideas from 'An Inquiry into Meaning and Truth'

16477 Asserting not-p is saying p is false [Russell]
16484 There are four experiences that lead us to talk of 'some' things [Russell]
16486 The physical world doesn't need logic, but the mental world does [Russell]
16483 Disjunction may also arise in practice if there is imperfect memory. [Russell]
16480 A disjunction expresses indecision [Russell]
16479 'Or' expresses hesitation, in a dog at a crossroads, or birds risking grabbing crumbs [Russell]
16481 'Or' expresses a mental state, not something about the world [Russell]
16487 Maybe the 'or' used to describe mental states is not the 'or' of logic [Russell]
16475 A 'heterological' predicate can't be predicated of itself; so is 'heterological' heterological? Yes=no! [Russell]
16482 All our knowledge (if verbal) is general, because all sentences contain general words [Russell]
16476 For simple words, a single experience can show that they are true [Russell]
16485 Perception can't prove universal generalisations, so abandon them, or abandon empiricism? [Russell]
16478 A mother cat is paralysed if equidistant between two needy kittens [Russell]
2947 Questions wouldn't lead anywhere without the law of excluded middle [Russell]
4758 Naïve realism leads to physics, but physics then shows that naïve realism is false [Russell]