From: jmc@SAIL.Stanford.EDU (John McCarthy)
Subject: Re: The Outer Limits
Reply-To: jmc@cs.Stanford.EDU
Organization: Computer Science Department, Stanford University
Date: 16 Dec 92 19:38:32

In article <149180168@hpindda.cup.hp.com> alanm@hpindda.cup.hp.com (Alan McGowen) writes:

   / hpindda:sci.environment / jmc@SAIL.Stanford.EDU (John McCarthy) / 12:23 am  Dec 11, 1992 /
   >To a technologically advanced society, not much more advanced
   >technologically and not at all more advanced scientifically than our
   >own, there is no such thing as permanent and continual accumulation of
   >pollution.  All the transformations of matter that humanity causes
   >both in manufacture and disposal conserve matter.  Except for the
   >production of radioactivity, they even preserve the amounts of the
   >various isotopes.  Therefore, if any substance, compound or
   >elementary, rises to troublesome proportions in any environment, it
   >can be transformed again to useful or at least innocuous forms, or
   >moved elsewhere.

   This is a protestation of faith, not the statement of a scientist. E.g. just 
   how do you remove bioconcentrating fat-soluable toxic substances for which 
   there are no metabolic pathways from food webs once they are introduced?
   McCarthy may *believe* that for every such substance, an artificial metabolic
   pathway could be genetically engineered into organisms, reworking the chemical
   functioning of whole ecosystems -- but this is just a sci-fi fantasy. We
   don't even know how many such substances there are nor what they are doing. 

   >This is my opinion, and I think it would be the majority opinion
   >of scientists and engineers if they contemplated the precise
   >question.

   Of scientists and engineers who are totally ignorant of biology and are
   unwilling to listen to what biologists say, perhaps -- but is it a good 
   idea to pay any attention to pronouncements about the living world from
   such people? People would do much better to listen to biological scientists,
   such as Paul Ehrlich, Edward Wilson, and Micheal Soule on such matters.

   McCarthy reasons as if the biosphere and all its biological processes were
   completely irrelevant to the question -- just do enough *work* (preferably
   generated by nuclear power) and any Humpty-Dumpty can be put back together
   again no matter how small the pieces he's been smashed into. 

   We don't have anything like that much power over the world, and won't have it
   anytime soon, if ever. McCarthy always assumes that the only "limits" we need
   to think about are the outer limits of basic physical law, never those imposed
   by the fabric of the biosphere itself. This crazy notion, if it could be 
   pursued far enough, would destroy the very biosphere it deems irrelevant. But
   far more likely, pursuing it would destroy *us* first. 

   ------------
   Alan McGowen

As he sometimes does, Alan McGowen has invented my position, but I do have
to say something about trace substances.  May I cite a biochemist, Bruce
Ames, who says that humans ingest more than 4,000 times as much
carcinogens (by the standard rodent test) from natural sources as
from all artificial sources.

I have read Edward Wilson only on sociobiology, insects and species diversity.
What does he say about trace substances?

I have read two books of Paul Ehrlich, _The Population Bomb_ and
_Population, Resources and Environment_.  The catastrophes predicted for
the 1970s in _The Population Bomb_ didn't occur, and I found
_Population, Resources and Environment_ flakey in a number of places.  For
example, it says that the second law of thermodynamics requires that
the biomass of a prey species exceed that of a predator.  The conclusion
is usually true though not always and has nothing to do with the second
law of thermodynamics, Ehrlich's venture into physics.  To the
extent that humans are a predator on chickens, it isn't true for us.
The biomass of the chicken population is less than the fraction of
human biomass it supports.

What does he say about trace substances?

I haven't read Michael Soule.  What does he say about trace substances?

Indeed no-one can guarantee humanity against all possible hazards,
but we have succeeded so far in dealing with those that reach
annoying proportions.  Moreover, the fraction of the economy required
to deal with real hazards has gone down over time.  Admittedly the
fraction dealing with imaginary hazards and real but minor hazards
has gone up.
--
John McCarthy, Computer Science Department, Stanford, CA 94305
*
He who refuses to do arithmetic is doomed to talk nonsense.