[lit-ideas] Re: The Educational Value of Slips of the Whatever
- From: Robert Paul <rpaul@xxxxxxxx>
- To: lit-ideas@xxxxxxxxxxxxx
- Date: Sun, 20 Sep 2009 20:21:49 -0700
Donal wrote (some time ago now)
More philosophically fundamental is P’s point that “winning” or the
degree of acceptance of an argument are [historical] _facts_, and
from these facts we cannot _deduce_ the _validity_ of what argument
is “winning”. We may guess, one way or another, but we cannot
_deduce_. This is enough to show there is a logical gap between
“winning” and “validity”.
If winning means 'acceptance,' I'd have thought that the history of
ideas from Aristotle's celestial mechanics to the acceptance of
phlogiston as necessary for combustion would have shown this. That
people accept and propose invalid arguments isn't really news.
When assessing “validity” we look for critical grounds, for what
actually ‘supports’ (non-inductively, of course) the argument or
theory under consideration. The answer is that whether an argument
is genuinely valid is always a guess of some sort. Even if some of
these guesses seem incontestable, the history of ideas is littered
with the supposedly incontestable that was then overturned, and,
perhaps more important philosophically, logically these guesses
cannot be demonstrated – even deduction itself, surely that most
sound of guesses, cannot be deduced deductively without the argument
being fatally circular.
If for some, deciding whether an argument is valid amounts to a guess,
a hunch, or a wild surmise, this would be an interesting fact about
those who proceed this way, not about how validity is determined. I
don't know what 'deduction itself' is supposed to mean: although
validity is predicated of deductive arguments in 'formal' logic,
validity itself is a simple notion that applies everywhere. An
argument is valid if and only if its premises could not jointly be
true and its conclusion false. 'Even if your premises were true, I
wouldn't have to accept your conclusion.' I've never heard of the
notion of validity itself being question. The underpinnings of a
formal system, the stopping places, cannot themselves be supported in
the way that the particular deductive moves they themselves support
are by them supported. But this doesn't mean there's some doubt as to
whether arguments of the form 'if p, then q, p, therefore q,' are
valid or not.
What happens when we worry about what lies behind the axioms of a
system is illustrated by Lewis Carroll's 'What the Tortoise said to
Achilles'
http://www.mathacademy.com/pr/prime/articles/carroll/index.asp
In truth we may often accept an argument _because it is valid_, but
it would be wrong to conclude that because we accept it the argument
therefore is valid.
Right. Was Richard questioning this?
Richard himself now appears appears
Perhaps valid arguments may be proposed for questions like "Is it
better to get up early or late in the morning?" Popper, I assume,
however, is more interested in questions of fact like "Is the
universe expanding?" And for that there are good and less good
arguments, but no "valid" arguments. The validity of arguments
about facts can only be judged by Laplace's Demon or a similarly
omniscient entity.
Laplace's Demon is invoked to support one simple-minded version of
determinism: suppose that such a demon knew everything (whatever that
might mean) about the past and present states of the universe. The
supposition is that such an omniscient creature would then be able to
predict all of its future states. This creature's knowledge would help
it to construct sound arguments, not merely 'valid' ones about
'facts,' and surely its the soundness of arguments that's here being
confused with validity. A sound argument is a valid argument whose
premises are true (however their truth is determined), and surely such
truth-supporting facts are essential to determining whether an
argument in, say, physics (where 'arguments' are perhaps more rightly
called explanations). Validity all by itself is not enough.
P would agree, I think, with this last sentence provided we
understand “judged” to mean “conclusively judged”. But we can, and
do, make provisional judgments about such facts. Even whether "Is it
better to get up early or late in the morning?". This question too,
insofar as we treat it as a question fact, cannot be conclusively
but only provisionally judged. Even where there are only "good and
less good arguments" [getting-up-early being a case in point;
science in general and metaphysics in particular being even more
crucial cases] we may still speak of validity, and even make
judgments as to validity, albeit in a non-conclusive sense.
Yes; but this doesn't mean that validity is problematic independently
of the factual claims that make up a putative valid argument. There's
some confusion about this throughout Donal and Richard's interesting
exchange. I hope I've added to it.
Robert Paul
The Reed Institute
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