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Re: Economists on ecology (Re: GOODBY MIKE!)



Jay Hanson  <jhanson@ilhawaii.net>, in response to the argument
   that we are not "running out" of resources:

>Our life-support system has its own requirements that have
>no relationship to markets. ^^^^^^^^^^^^^^^^^^^^
>^^^^^^^^^^^^^^^^^^^^^^^^^^^

Jay, the activities humans choose to undertake depend critically on the
incentives they face.  The incentives they face in many cases -- and in
particular in the case of resource extraction -- depend on prevailing and
expected prices.  Hence, the impact humans have on the environment _does_
depend on the behavior of markets.  I don't see how any reasonable
observer can deny this fact.

Since resource extraction is a human activity and human activity is the
realm of social science, it would certainly appear that both natural _and_
social science are relavant to understanding human impact on the
environment.  This does not imply, as you continually assert, that
economists fail to consider the fact that human life depends on (and
indeed, is part of) the environment. 

Consider an analogy.  Mathematical epidemiology generally takes rates of
contact as given when modeling the spread of a disease.  Economists point
out that that assumption is wrong in the case of many diseases (for
instance, AIDS): as the probability of becoming infected rises, people
will respond to the change in incentives by changing their behaviour,
thereby affecting the course of the disease.  Thus, a model which failed
to account for behavioral change would give misleading predictions.

Similarly, an ecological model which fails to account for the fact that
people will change their behaviour as prices change will be misleading. 
Of course, we still need ecological knowledge to understand the system,
but if we ignore economic knowledge we will get things systematically
wrong.  Continuing the analogy: if we based a forecast of long-run disease
prevalence on _given_ behavior we would almost surely overpredict, much
like basing an estimate of "carrying capacity"  on _given_ behavior will
be wrong (as others have pointed out, it isn't at all clear that "carrying
capacity" even has any relevance to human populations since, essentially,
technology and its use is endogenous).  In both cases, the prediction
based on _given_ behavior is wrong because it fails to take into account
the interaction between human action and the results of those actions. 

Simple epidemiological models predict that 100% of the population will
eventually become infected, whereas such a model augmented with an
economic model of behavior would predict less than 100% steady-state
prevalence.  I leave it to you to deduce the direct analogy to resource
extraction (evaluate, for example, "We will run out of coal in 2012.") 

>That is why ecologists do not care what economists [...] think about the
>environment -- they go through life looking at things ass-backwards.

Jay, could you please name some ecologists who "do not care what
economists think about the environment?"  Why do these ecologists not
believe that social scientists might have something useful to say about
human behavior?  Or do they deny that human behavior affects the
environment?


Aside: anyone interested in economic epidemiology should read _Private
Choices and Public Health_ by Philipson and Posner (Harvard 1993). 

Shameless plug: people might also be interested in my paper "Choices,
Beliefs, and Infectious Disease Dynamics," Queen's Working paper #938,
October 1996. 

-- 
Chris Auld                               Department of Economics
Internet: auld@qed.econ.queensu.ca       Queen's University
Office:   (613)545-6000 x4398            Kingston, ON   K7L 3N6   


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