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Re: Underdetermination and Scientific Realism

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Dear Matthew,

'Confirmatory' is a standard piece of vocabulary which means something like what
you mean by 'supporting'. So confirmatory evidence need never be taken to mean
indefeasible evidence.

If you have concerns about the duck pond example, then I have another kind of
example which makes the same point: that not all positive instances of a
theory's empirical consequences are confirmatory. Imagine a mystic who
hypothesises that "joy is the transcendance of noise outside of death". The
mystic supplements this hypothesis with a conditional: "If joy is the
transcendance of noise outside of death then summer will follow spring". Each
instance of summer following spring is a positive instance of the theory, but
surely not a confirming instance.

Nick

Quoting Matthew Hodgetts <matthew.hodgetts@gmail.com>:

> Just one thought- I would have thought that seeing the (same) ducks
> *is *confimatory
> evidence, even if only weakly so. Perhaps rather than talking about
> 'confirmatory' evidence it might be better to say 'supporting' evidence.
> 'Confirmatory' sounds to me a bit too much like it's offering undefeatable
> evidence for an hypothesis, whereas no theory is actually ever totally
> immune from future revision, at least in principle, if not in practice.
> 
> M.
> 
> 
> On 24/03/06, N Tasker <pia03nt@sheffield.ac.uk> wrote:
> >
> > To reply to this message or start a new topic please email:
> > BUPS-DIS@bups.org
> >
> >
> >
> >
> > Much attention has been given to defending scientific realism from the
> > underdetermination thesis (UT), while the truth of the thesis itself seems
> > to
> > have been accepted as obviously true. I believe that UT is often expressed
> > ambiguously, and that shoring up the thesis in such a way that it poses a
> > genuine challenge to realism renders it beyond rational defence.
> >
> >     Scientific realism: the doctrine that there exists a world beyond our
> > observation which it is the aim of science to correctly describe, and that
> > it
> > is generally successful in doing so. Moreover, we are capable of
> > discerning
> > when a theory is correct in describing the unobservable world.
> >
> >     The underdetermination thesis: for any given scientific theory, t,
> > there
> > will be an indefinite number of theories which are incompatible with t,
> > and yet
> > which are equally well supported by the evidence as t. UT is supposed to
> > threaten realism since we can never be in a position to know that we have
> > thought of the correct theory.
> >
> > The problem with UT is that the phrase "equally well supported by the
> > evidence"
> > is ambiguous. One popular suggestion is that a theory is supported by
> > observed
> > instances of its empirical consequences. So, for example, the theory that
> > water
> > boils at 100 degrees implies that this pot of water should boil when it
> > reaches
> > 100 degrees. When this event is observed, then we have a confirmatory
> > instance
> > of the theory. The assumption here is that 'positive instance' =
> > 'confirmatory
> > instance'. Given this assumption, I think UT does pose a challenge to
> > realism.
> > Unfortunately for UT, this just isn't how science works.
> >
> > I assert (a) that not all positive instances of a theory are confirmatory,
> > and
> > (b) that not all confirmations of a theory come from observations of its
> > positive instances.
> >
> > Argument for (a): imagine you and I are sitting by a duck pond. I notice
> > that
> > all the ducks in the pond are male, and I hypothesise that all ducks in
> > the
> > world are male. Naturally you ask me to support my hypothesis. I reply
> > that all
> > positive instances of a theory are confirmatory, and therefore, the very
> > same
> > ducks which initially prompted my hypothesis count as good evidence for
> > it.
> >
> > Argument for (b): scientists take into account other virtues when
> > assessing
> > theories, e.g. coherence with other theories, consilience, predictive
> > power, no
> > ad hockery.
> >
> > So just because two theories have the same empirical consequences, that
> > doesn't
> > mean that they are equally well supported. If the argument against realism
> > is
> > to have any force it must assert that there will be an indefinite number
> > of
> > equally well supported theories, when 'support' is defined in the way I
> > have
> > gestured towards. But the arguments one tends to encounter for UT entitle
> > it to
> > a much cruder definition of 'support', a definition which assumes that all
> > and
> > only positive instances of a theory are confirmatory.
> >
> > Take for example the Kripkensteinian argument about rule following. For
> > any
> > sequence of numbers there will be many different functions which describe
> > different ways of continuing the sequence, and which are equally well
> > supported
> > by the original sequence. However persuasive this reasoning may be in
> > mathematical examples, this way of justifying UT seems to assume the
> > fallacious
> > principle of confirmation which I diagnosed above.
> >
> > Does anyone know a better way of arguing for UT ? one which better
> > approaches
> > the true nature of confirmation in science?
> >
> >
> > Browse or search the BUPS-DIS archives, or unsubscribe from the mailing
> > list at: http://www.bups.org/mailinglist.shtml
> >
> 




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