Anthropology and science

John McCreery (JLM@TWICS.COM)
Wed, 4 Oct 1995 11:46:19 +0900

"The laws explored three centuries ago have not changed
because our ideas have changed (gravity is not subject to
our whim and we do not fly like birds in the sky), they have
served as foundations to make new laws, that describe the
universe in a more objective manner."

Allan, I'm on your side, but this is a little too facile. The law
of gravity is a first-class example of a law that has
changed. Einstein's theory of relativity not only made
Newton's formulation more precise ( accounting, in the
most famous example, for the apprent orbit of Mercury) it
also changed fundamentally the way in which gravity is
conceptualized: as a bend in the geometry of space instead
of a force acting at a distance. Practically speaking there is
no difference unless you are moving close to the speed of
light, but the difference is real.

A similar example famous in the history of science is the
difference between the Ptolemaic and Copernican
approaches to accounting for the movement of heavily
bodies. As Birt (_The Metaphysics of Modern Science_)
pointed out way back in the pre-postmodern '50s, Ptolemy's
scheme is every bit as accurate as Copernicus's, and since
Copernicus postulates circular orbits, he,too, was forced to
resort to epicycles to account for some planetary motions.
Worse still, his theory predicted stellar parallax, which
wouldn't become observable until the invention of the
telescope. At the time Copernicus was writing, a hard-
nosed empiricist would have been perfectly justified in
sticking with Ptolemy!


John McCreery