Steve Witham wrote:

...

Models can often be very fruitful even when they highly oversimplify things.

From: Robert Baillie <rjbaillie@frii.com>

granted, but even there, economics falls on its face: unlike physicists, economists cannot predict the future.

I wouldn't call that falling on its face, I'd call it not being physics. Recently I've been inspired to learn more about economics and its status. One book high on my list is Mises "The Ultimate Foundation of Economic Science," which seems to be about why trying to emulate physics is inappropriate for economics. It's free online in both html and pdf: http://mises.org/books/ufofes --Steve