Re: reductio ad falsum versus reductio ad absurdum


Torkel Franzen wrote:
> "futurist" <adamgolding@xxxxxxxxxxxxxxx> writes:
>
> > these two modes of reasoning seem fundamentally different to me, and
> > thus seem to deserve separate names in ND, which is supposed to model
> > natural reasoning, after all.
>
> But we use exactly the same rules in proving results of the form
> G=>~A and in proving results of the form =>~A.

indeed--i suppose i'm objecting more the appropriateness of the english
and latin names in the way they are currently mapped onto the logical
rules.

when i hear 'contradiction' i tend to assume 'self-contradiction' ..
i.e. the 'statment' which is sometimes represented by 'F' is said to be
a 'contradiction' meaning that it is a 'self-contradiction'--similarly
with more specific contradictions, i.e. P&~P, and so on. thus, it
would seem, for consistency's sake, that 'proof by contradiction'
should be sort for 'proof by self-contradiction'--furthermore
'reduction ad absurdum' is suppose to be 'poof by contradiction' and
thus RAA should be 'proof by self-contradiction'.

if there is a rule in ND which covers both what RAA and RAF should mean
in english latin, that rule should be given a more general name which
does not make it seem more specific than it is.

also, the result G=>~A could concievably be proven in either way--by a
self-contradiction in A, or by a contradiction between A and G--so i
suppose what i said earlier about the essential differenct--what
matters is not so much whether there *are* premises, but whether the
premises are required to generate the contradiction.

.

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