Subject: Re: Open letter to those who believe in a right to free software
From: Richard Stallman <rms@gnu.org>
Date: Sat, 30 Oct 1999 07:16:27 -0600 (MDT)

	rms> But that just puts the hard part of the issue into figuring
	rms> out the preference function.

    Not hard at all.  Trivial, in fact.

    Measure it.

You could in principle measure a person's preferences for alternatives
that arise frequently.  (Doing this in practice may be quite
difficult, but mathematical theorists often regard this kind of
difficulty as trivial.)

But when alternatives arise rarely, it is hard to measure a
probability or assign a utility function empirically.  The data is not
good enough to support one.

And some of the alternatives that may occur in the future have never
occurred before.  There is no way to measure what people think of
them.  The only way to anticipate what people will do about such
situations is to think about how they think about issues.

It is not enough to know what people think today--what they think in
the future may be different, because people change their minds.
Sometimes because they are persuaded by arguments offered by other
people.  So it is necessary to include the way ideas are communicated
and discussed in the model.

Some microworlds can be modelled effectively without taking all this
complexity into account.  But there are limits to how far that
approximation is valid.  It can't model politics.

If you could model politics with an economic model, I think you would
probably find it is a chaotic system, and the model cannot predict
beyond the very near term.