Wittgenstein and (x).fx

Question

I'm currently reading Ludwig Wittgenstein's posthumous Remarks on the Foundations of Mathematics, and one example he keeps using is the logical inference of 'fa' from '(x).fx'

What does this inference mean, or rather what does the notation '(x).fx' indicate?

score 8 · Answer 1 · answered Jan 20 '13 at 19:32

8

His notation $(x).fx$ would today usually be written $\forall x\colon f(x)$. If something holds for all $x$, then it also holds for a specific object $a$, i.e. we can infer $f(a)$ from $\forall x\colon f(x)$.

answered Jan 20 '13 at 19:32

Hagen von Eitzen

374,180

score 6 · Accepted Answer · answered Jan 20 '13 at 19:33

6

You might look here: http://plato.stanford.edu/entries/wittgenstein-atomism/

"(x). fx = logical product[9] (of all propositions of the form fx) fa.fb.fc…"

answered Jan 20 '13 at 19:33

user58437

1,014

Wittgenstein and (x).fx

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