Posted by dorayme on 12/08/07 22:59

In article <slrnflkpn8.775.spamspam@bowser.marioworld>,
Ben C <spamspam@spam.eggs> wrote:

> On 2007-12-08, dorayme <doraymeRidThis@optusnet.com.au> wrote:
> [...]
> > There is only one particular arrangement of truth and falsity in
> > a valid argument that is ruled out, namely the combination of
> > true premises with false conclusion. Any argument that is known
> > to have true premises with a false conclusion is thereby known to
> > to be invalid. It is a bad argument by being invalid. The
> > conclusion does not follow from the premises.
> >
> > The condition of an argument being valid is simply this: if the
> > premises are true, the conclusion must be. This says nothing
> > about the truth of either the premises or the conclusion. How to
> > know the truth of the premises is entirely out of the scope of
> > any one argument being assessed.
>
> > A reductio is a rather special sort of argument, it is a sort of
> > meta argument in which people are invited to look at how more
> > normal arguments within play themselves out.
>
> I think the point of a reductio ad absurdum is usually to show the
> premises are false. They might not look false on their own, so you show
> that they imply something which is obviously absurdly false. If the
> argument is valid that means the premises must be false since true
> premises cannot imply a false conclusion.

Yes. In one of my replies I said "This type of argument is
sometimes called a reductio ad absurdum". Strictly a reductio
assumes the truth of something and derives an actual
contradiction by exact reasoning from it. There are some
breathtaking examples in mathematics going back as far as Euclid.
It is a beautiful thing to behold.

But my reply to gent who seemed to be in favour of frames for a
limited purpose of achieving OPs aim was not quite of this pure
kind. It was an invitation to reject his view expressed in
premises 1 and 2 because they lead, along with some very
reasonable other assumptions, to 7 and 8. Neither 7 nor 8 were a
direct contradiction of either 1 or 2. Its purpose was to say, in
a way, do you really think that the very clear consensus is that
using target="_blank" is a BAD THING is wrong? Naturally some one
could turn around and say yes.

Next time I will try to more carefully offer a strict reductio.
But I know there are several people ready to shoot me good and
proper if I were to go on to attempt it now... <g>

--
dorayme

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