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From: cik@l.cc.purdue.edu (Herman Rubin)
Newsgroups: comp.ai,sci.philosophy.tech
Subject: Re: How to dispose of naive science types (short)
Summary: All useful theories are in some way false.  But how false?
Keywords: open your eyes next time you leave the lab
Message-ID: <850@l.cc.purdue.edu>
Date: 25 Jul 88 12:02:06 GMT
References: <483@cvaxa.sussex.ac.uk> <794@l.cc.purdue.edu> <488@aiva.ed.ac.uk> <6032@bunny.UUCP>
Organization: Purdue University Statistics Department
Lines: 40

In article <6032@bunny.UUCP>, rjb1@bunny.UUCP (Richard J. Brandau) writes:
> > gilbert@cs.glasgow.ac.uk (Gilbert Cockton) writes:
> > Please explain to me how an unproveable theory (one that makes no unique
> > predictions) can be useful?

< Perhaps you mean a NONDISPROVABLE theory.  An "unproveable" theory is
< a very special thing, often much harder to find than a "proveable"
< theory.  If you can show that a theory is unprovable (in some axiom
< set), you've done a good day's science.

> No theories make "unique predictions" about the real, (empirical)
> world.  Are quarks the ONLY way to explain the proliferation of
> subnuclear particles?  Perhaps a god of the cyclotron made them
> appear.  The difference between the scientific and religious theories
> is that the scientific one can be DISproven: it makes predictions that
> can be TESTED.
> 
> You may, if you like, apply this distiction to the beliefs that
> determine your behavior.  Since you can't disprove the existence of
> God, you may choose to chuck out all religion.  Since you CAN think of
> ways to disprove f=ma, you may avoid being run over by a bus.

It is recognized that any non-trivial complete theory cannot be exactly true.
If I say that there will be some history of the universe, this is a trivial
untestable theory, and is completely useless.  If I say that the motion of
the planets is describable by Newton's law of gravity, this is clearly false,
but is quite adequate for spaceship navigation.  Even with relativistic
corrections it is false, because it ignores such things as tidal friction.
Furthermore, we do not know the precise form of gravitation in a relativistic
framework, and even less the modifications due to quantum mechanical considera-
tions.

In the strict sense, we will never have a correct theory.  The proper question
about a theory is whether its errors should be ignored at the present time. 
And it is quite possible that for some purposes they should and for others
they should not.  But unless the theory provides predictive power or insight,
its accuracy is unimportant.
-- 
Herman Rubin, Dept. of Statistics, Purdue Univ., West Lafayette IN47907
Phone: (317)494-6054
hrubin@l.cc.purdue.edu (Internet, bitnet, UUCP)