Vladimir Nesov wrote:
On Mon, Jun 2, 2008 at 6:27 AM, Mark Waser <[EMAIL PROTECTED]> wrote:
But, why "SHOULD" there be a *simple* model that produces the same
capabilities?
What if the brain truly is a conglomeration of many complex interacting
pieces?
Because unless I know otherwise, I use simplicity-preferring prior.
Biological complexity is hardly evidence that the refined
computational model is also complex. It is very easy, as J. Rogers
noted, to scramble a simple object so that you won't ever guess that
it's simple based just on how it looks on the surface.
This misses the point I think.
It all has to do with the mistake of *imposing* simplicity on something
by making a black-box model of it.
For example, the Ptolemy model of planetary motion imposed a 'simple'
model of the solar system in which everything could be explained by a
set of nested epicycles. There would have been no need to use any other
model because in principle those epicycles could have been augmented to
infinite depth, to yield as good a fit to the data as you wanted.
That is a black-box model of the solar system because it stuffs all the
real complexity inside a black box and then models the black box with a
simplistic formalism. If all you care about is getting a precise model
of planetary movement across the sky, this would be (and was!) the
simplest model anyone could ask for.
But it was wrong. It was wrong because it obscured the real situation.
The real situation could not be understood without inventing a whole
new type of mathematics (calculus) and discovering a new law of nature
(universal gravitation). By any measure, that combination of calculus
and gravitation was a more "complicated" explanation.
Anyone at the time who knew that Isaac Newton was trying to do could
have dismissed his efforts and said "Idiot! Planetary motion is simple.
Ptolemy explained it in a simple way. I use simplicity-preferring
prior, so epicycles are good enough for me."
And if that same person insisted that there SHOULD be a simple model of
planetary motion (where "simple" meant 'as simple as epicycles") would
have been insisting that an explanation as complicated as calculus and
gravitation was in some sense bad or unparsimonious.
In the long run, of course, gravity plus calculus was perceived as being
'simple' and elegant in the extreme. But that is not the point, because
before it was discovered it could have been criticised as being far, far
more complicated than the epicycle explanation.
What Rogers was suggesting was that a 'simple' black-box explanation was
already a good explanation for neurons. Quite apart from the fact that
such a model has not even been created yet (!), even if it did exist, it
would amount to nothing more than an epicycle explanation.
Richard Loosemore
-------------------------------------------
agi
Archives: http://www.listbox.com/member/archive/303/=now
RSS Feed: http://www.listbox.com/member/archive/rss/303/
Modify Your Subscription:
http://www.listbox.com/member/?member_id=8660244&id_secret=103754539-40ed26
Powered by Listbox: http://www.listbox.com
