From: dean@vexcel.com (Dean Alaska)
Subject: Re: free Beyond the Limits program
Organization: VEXCEL Corporation, Boulder CO
Date: Sun, 13 Dec 1992 20:05:01 GMT

In article <JMC.92Dec12115854@SAIL.Stanford.EDU> jmc@cs.Stanford.EDU writes:
>In response to my question as to whether the _Beyond the Limits_ simulation
>allows the user to assume that *any* desired chemical transformations
>of pollution and other materials can be achieved Dingo includes:
>
>     Whether or not its eventually possible to transform or move
>     all troublesome pollution, it either isn't possible or
>     economical to do so now, so the model represents the current
>     reality, unless you believe that there is no troublesome
>     pollution now.
>
>There is a question of the time-scale of the simulation.  If a
>simulation purports to cover a time longer than it takes technology
>to change, then it is unrealistic not to take technology change into
>account.

Well, it does.  But is assumes that the new technology takes time to
develop, costs money to develop and costs money to implement.  Your
previous question was about whether the model could be adjusted to
represent a world with _no_ troublesome pollution, not about whether
it takes new technology into account.
>
>In response to my question of whether human reaction to nuisances
>could be incorporated by a user and my grumble that the extreme
>aggregation enforced by the model made this difficult, Dingo included
>
>     Since impacts vary in type and cost, it seems that the
>     aggregate approach would be more accurate since it can take
>     advantage of a larger sample space of impacts.  Also, if the
>     response to these nuisances is to attempt to develop
>     technological solutions, then there is a common denominator
>     in analyzing impacts since such development requires that
>     both capital and labor be removed from other activities.
>
>It is much more realistic to argue about whether CO2 in the
>atmosphere can be adjusted to human convenience than to make
>a general argument about aggregate pollution.  Indeed reducing
>nuisances or avoiding them requires capital and labor.  Therefore,
>estimating the costs of one or the other should be a decisive
>consideration, and a realistic simulation model should permit
>assumptions about these costs as well as assumptions about how
>humans will react to nuisances.

Estimating labor and capital costs is important, but such costs can
be more accurately estimated statistically than they can be individually.
That is the advantage of the aggregate method.  While the specific cost
of dealing with a particular environmental problem are very relevant to
discussions about such actions, it is less relevant to questions about
general carrying capacity.  Some problems will cost more, some less.
>
>Purely qualitative arguments saying "if this or that continues
>long enough we will all die, and therefore we must take action
>right away" are no good, because there are too many such
>phenomena, and we have to sort them out.  Without quantitative
>reasoning, what is done is determined merely by what lobby with
>a particular hobby can shout the loudest.
>
>After all, if Dingo continues sitting in his chair at his terminal he
>will surely fall off the chair and die in less than a month.  However,
>we don't have to shout at him to get up, because we are confident that
>he will get up as soon as sitting gets uncomfortable.

Humans are well adapted to recognizing hunger.  I can respond to this
hunger before I will die, so noone needs to warn me.  How well are we
adapted to responding to environmental problems that develop over
decades and whose responses to corrective actiona also have similar
delays?  If I would die in a month without food but it took 6 weeks
for me to digest food, then I would need the warning to eat before I
got hungry.  The model is not purely qualitative.  Its quantitative aspects
are certainly open to question, as has been invited by the authors.  The
many parameters are undoubtedly subjective to some degree.  As with GCM's,
we cannot be certain that such models are correct when they extrapolate.
In the more recent book, _Beyond the Limits, the authors claim that the
published results from the first book closely match the historical
experience since then, which is about nas good a validation as is
available now.
>--
>John McCarthy, Computer Science Department, Stanford, CA 94305
>*
>He who refuses to do arithmetic is doomed to talk nonsense.
>


-- 

		dingo in boulder	(dean@vexcel.com)