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Full Idea
By a 'propositional function' I mean something which contains a variable x, and expresses a proposition as soon as a value is assigned to x. That is to say, it differs from a proposition solely by the fact that it is ambiguous.
Gist of Idea
'Propositional functions' are ambiguous until the variable is given a value
Source
Bertrand Russell (The Theory of Logical Types [1910], p.216)
Book Ref
Russell,Bertrand: 'Essays in Analysis', ed/tr. Lackey,Douglas [George Braziller 1973], p.216
A Reaction
This is Frege's notion of a 'concept', as an assertion of a predicate which still lacks a subject.
Related Idea
Idea 8488 A concept is a function whose value is always a truth-value [Frege]
| 23457 | Type theory cannot identify features across levels (because such predicates break the rules) [Morris,M on Russell] |
| 21556 | Classes are defined by propositional functions, and functions are typed, with an axiom of reducibility [Russell, by Lackey] |
| 21566 | 'Propositional functions' are ambiguous until the variable is given a value [Russell] |
| 21567 | 'All judgements made by Epimenedes are true' needs the judgements to be of the same type [Russell] |
| 21568 | A one-variable function is only 'predicative' if it is one order above its arguments [Russell] |