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From: amigo@iwlc6.UUCP (John Hobson)
Newsgroups: net.origins
Subject: Re: Occam's Razor - A Popular Fallacy?
Message-ID: <129@iwlc6.UUCP>
Date: Fri, 13-Apr-84 10:06:39 EST
Article-I.D.: iwlc6.129
Posted: Fri Apr 13 10:06:39 1984
Date-Received: Sun, 15-Apr-84 06:25:40 EST
References: <1032@ihuxr.UUCP>
Organization: AT&T Bell Labs, Naperville, IL
Lines: 37

Krista Anderson asks:
>>	Are you *sure* Occam's Razor is a valid principle?  I see
>>	it used frequently by both sides in creation/evolution
>>	arguments.  It states something like if two explanations
>>	work equally well, the simpler of the two should be chosen
>>	for belief.

>>	If that is true, can anybody show me why it's true?  For
>>	example, we see the sun travel across the sky daily.  A
>>	simple explanation might be that the sun revolves around
>>	the earth, but most of us know that the more accurate
>>	explanation is a bit more complicated. 

Occam's razor (named for the medieaval philosopher and theologian
William of Occam [or Ockham]) basically says that if you have two
explanations which cover *all the known facts*, then choose the
simpler of the two (the formal statement is that entities should
not be multiplied unnecessarily).  It is more a rule of thumb than
a universal truth, but it is generally accepted as being
intuitively obvious.

Indeed, to use Krista's example, the earth going around the sun was
accepted as being the simplest explanation for many thousands of
years.  However, when more facts about the positions of the planets
became known, the whole system of epicycles that was needed to
predict their orbits just became too cumbersome (Rube Goldberg
would have loved it), and the heliocentric system was accepted
because it simplified the mathematics considerably.  Remember,
Johannes Kepler was a firm proponent of the belief that the planets
had circular orbits.  He abandoned epicycles in favour of
elliptical orbits simply because the orbital mechanics of ellipses
gave better results (fit the known facts better).

				John Hobson
				AT&T Bell Labs--Naperville, IL
				ihnp4!iwlc6!amigo