fom wrote: > On 10/19/2013 6:23 AM, Peter Percival wrote: >> Nam Nguyen wrote: >> >>> What definition of "invalidity" were you referring to _here_ ? Mine? >> >> If you use the word "invalidity" is newsgroups called sci.logic and >> sci.math then it should probably be with its usual technical meaning. If >> you use it in another sense you should probably say what sense that is >> right from the start. >> > > It does get confusing, doesn't it? Given that Nam's apparent > views are epistemic and modal,
And yet he refuses to say what is epistemic and modal assumptions are, though he is fond of the phrase "impossible to know".
> his use of "validity" probably > correspond with "necessity" in some system of frames. Generally, > modal logic is based on classical logic and frame systems simply > incorporate mathematical necessity into all worlds. But, since > Nam is applying the modal reasoning to the reasoning of mathematics > itself, truths on the basis of valid proofs are not necessary. > And, if this can even be made to work at all in some system of > frames, those truths would not be valid in the semantic sense > as the notion would be conflated with necessity. > > Key counterfactual: > > ... if this can even be made to work at all... > > >
-- The world will little note, nor long remember what we say here Lincoln at Gettysburg