[extropy-chat] Inside Vs. Outside Forecasts

Robin Hanson rhanson at gmu.edu
Tue Oct 11 21:34:34 UTC 2005

At 02:48 PM 10/11/2005, Hal Finney wrote:
> > The application to our forecasts about the future should be obvious:
> > Do we overestimate technical change because we tend to take an inside
> > view, imagining the particular process that produces some innovation,
> > instead of an outside view, looking at how long similar innovations have
> > taken in the past?
>I am inclined to think that this is not the reason.  I may not fully
>understand this distinction, but it sounds like the "inside view" is based
>on analysis from a position of some expertise and detailed knowledge of
>the problem domain.  Scenarios and extrapolations are constructed based
>on this detailed knowledge.

That is not how I read the distinction.  It seems to me more about imagining
a story about the process.  So people basing their forecasts on science
fiction novels would count as an inside view.  But I won't know for sure
until I can read the paper.

>I suspect that the world has changed, that it has fallen off the
>exponential curve.  The real shape is an S curve, the logistic curve
>of yeast growth.  It is hard to tell the two apart as you move through
>the inflection point.  We were using a reasonable methodology in making
>predictions, but it assumed continued exponential or even hyperbolic
>growth.  That was in fact a fair reading of the history of humanity up
>through the early 20th century. ...
>Who could have predicted that, after centuries of accelerating change?

It seems to me that change has not really accelerated in the twentieth
century.  In many ways change was faster in the first half of last century.
There is an academic literature on economic growth and technical change and
it seems to me that the standard views in those literatures is of roughly
steady, not accelerating, growth.  Yes, over billions of years change has
accelerated, but not continuously.  Instead, growth rates have remained
steady until they reached transition points where they then jumped by two
orders of magnitude (http://hanson.gmu.edu/longgrow.pdf).

Another big transition may well happen this century, to a much faster growth
rate.  But until that transition I expect steady growth to continue.

Robin Hanson  rhanson at gmu.edu  http://hanson.gmu.edu
Associate Professor of Economics, George Mason University
MSN 1D3, Carow Hall, Fairfax VA 22030-4444
703-993-2326  FAX: 703-993-2323 

More information about the extropy-chat mailing list