On Jun 26, 2007, at 8:31 AM, Robert Holmes wrote:
> Epstein has a new book and MIT Tech Review are running an article on
> artificial societies on the back of it
>
> http://www.technologyreview.com/Infotech/18880/page1/
Well, I bought the book, because of our teaching the SFI modeling
section, and wanted to have it as a reference. It seems reasonable
enough .. covering an interesting spectrum of what we all are
prodding at and not a "popular" book as much as a survey of
techniques and history for practitioners. I like the structure of
the book as well -- basic classics preceded by a unifying preface.
Prefer NOT to have the CD, a web site would be better. I suspect
it'll be a classic.
> And again, there's that old chestnut: these models explain, not
> predict. Do
> we still believe this? I agree - they do not predict, but do they even
> explain? I'm getting increasingly troubled about this whole notion
> that the
> rules the researcher puts in the agents actually have some sort of
> analog in
> actual people. Even when conclusions are presented as "this is AN
> explanation" not "this is THE explanation", I suspect that the ABM
> researcher is being somewhat optimistic.
You're being a bit unfair: the entire paragraph is:
.....
Altogether, in fact, Epstein stressed that his models were
mostly aimed at achieving explanatory power. "To explain something
doesn't mean that you can predict it," he said. He pointed out that
though we can explain lightning and earthquakes, we can't forecast
either. If we're hoping, like Asimov, to predict the future,
Epstein's models will disappoint. In fact, because his models give
widely divergent results even when their agents are programmed with
very simple rules, they indicate that predicting the future will
never be possible. Still, Epstein's artificial societies do more to
make plain the hidden mechanisms underlying social shifts--and their
unexpected consequences--than any tool that social scientists have
hitherto possessed. In the future, they and others like them could
suggest how policymakers can engineer the sorts of small, cheap
interventions that have large, beneficial results.
.....
Physics, in other words, has many of the same difficulties when
considering ensembles. Its quite reasonable for us as well. Yet we
don't dis physics when it can't predict details, only explain
behavior, in say statistical mechanics.
> So what is the relationship between the rules in the artificial
> agents and
> the rules in real people?
>
> Robert
At the summer school this year, Tom Carter made a great point:
Consider the narrative of your model .. the story it tells and the
story you will tell as you explain it to others as the model evolves
before their eyes. So in the Schelling model of segregation, you
can't predict which neighborhood will become a ghetto, but you can
predict with near-statistical-mechanics-certainty that segregation
will occur. And all with a simple preference behavior.
-- Owen
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