Tractatus Logico-Philosophicus (English): Difference between revisions

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5.5301 That identity is not a relation between objects is obvious. This becomes very clear if, for example, one considers the proposition "(''x'') : ''f x'' . ⊃ . ''x'' = ''a''" What this proposition says is simply that ''only'' ''a'' satisfies the function ''f'', and not that only such things satisfy the function ''f'' which have a certain relation to ''a''.
5.5301 That identity is not a relation between objects is obvious. This becomes very clear if, for example, one considers the proposition "(''x'') : ''f x'' . ⊃ . ''x'' = ''a''" What this proposition says is simply that ''only'' ''a'' satisfies the function ''f'', and not that only such things satisfy the function ''f'' which have a certain relation to ''a''.


One could of course say that in fact ''only''  has this relation to  but in order to express this we should need the sign of identity itself.
One could of course say that in fact ''only'' ''a'' has this relation to ''a'' but in order to express this we should need the sign of identity itself.


5.5302 Russell's definition of "=" won't do; because according to it one cannot say that two objects have all their properties in common. (Even if this proposition is never true, it is nevertheless ''significant''.)
5.5302 Russell's definition of "=" won't do; because according to it one cannot say that two objects have all their properties in common. (Even if this proposition is never true, it is nevertheless ''significant''.)