From: nickh@CS.CMU.EDU (Nick Haines)
Subject: Philosophy of Science (was Re: dragons were dinosaurs?)
Originator: nickh@VOILA.VENARI.CS.CMU.EDU
Organization: School of Computer Science, Carnegie Mellon University
Distribution: rec
Date: Fri, 21 Aug 1992 23:29:22 GMT

Can you lot calm down a bit, please?

Go get yourselves a good introductory textbook to the history and
philosophy of science, sit down somewhere quiet, read, learn, and
inwardly digest. Find out what different scientists thought (and
think) is meant by "scientific fact," "knowledge," "theory" and so on.
Then maybe we can have a reasonable discussion here and stop using
nonsense terms like "scientific impossibility," or talking rubbish
about "experts" in the shape of the Earth at the time of Columbus.

- Scientific theories are _not_ "facts," but predictive models of the
universe. They may or may not have anything to do with underlying
mechanisms, "physical laws," the will of God, or the price of tea in
China.

- Newtonian gravity (for instance) is not a "scientific fact" now, and
_never_was_, not because it is wrong but because it was a model.
Scientific facts are things like "the apple fell from the tree."

- General relativity and QCD (for two more instances) are no more
"facts" than Newtonian gravity (or Platonic natural philosophy) are
(or ever were) facts. Neither are impact hypotheses to explain
mass extinctions.

For all we know, the outcome of every scientific experiment is
determined by invisible elves, or by God playing dice, or is written
up in a big book on a planet in the Lesser Magellanic Cloud, entitled
"The Next 20 Billion Years, or What I Did After Breakfast". For all we
know, dinosaurs decided to leave the planet in a big rocket and fake
lots of old bones as a joke. Or maybe there "really are" such things
as electrons, W bosons, vacuum fluctutations, (massive?) neutrinos,
and mass extinctions.  I don't know, and you don't know. They're all
models. They happen to fit the results pretty well: better than, say,
phlogiston theories. I have _faith_ in the predictions of these
models, because they fits the results (my experiences) so well,
because they're neat mathematically, and because they don't have too
many redundant flights of fancy. But I don't think they're "facts,"
and neither do the people at the forefront of the field who keep
coming up with new and _better_ models.

One such new model says "all large land animals died out 65 million
years ago following a major impact event." It fits the facts very
well, better than any we've had before, and has demonstrated
predictive power (predicting that a major impact site would have that
date). A consequence of the model is that dinosaurs did not survive to
interact with genus homo. Since we have no evidence to contradict this
consequence, and since the model is currently our best, our faith in
the model carries over onto the consequence. OK?

An extension of the same model is the Nemesis hypothesis. This has
predictive power ("the sun has a companion star" for a start) but
there's no substantial evidence on either side yet. I could extend the
model in other ways: "an intelligent race didn't like the look of what
was evolving on Earth so dumped on us." Anyone want to write that one?

As for "where did the myths come from?", try asking the same question
about some of the other fabulous creatures in medieval (and earlier)
legends. How about engravings of people (supposedly seen by explorers
in Africa) with mouths in their chests? How about gryphons?

Oh, and please don't try stretching comparisons between the state of
science today and that 500 years ago. It just makes you look dumb.

Nick
Newsgroups: rec.arts.sf.science