On 8/2/2012 3:38 PM, Russell Standish wrote:
On Wed, Aug 01, 2012 at 01:24:59PM -0400, John Clark wrote:
On Wed, Aug 1, 2012 at 8:04 AM, Russell Standish<li...@hpcoders.com.au>wrote:

Flipping a coin is never rational, although it may well be the best thing
to do.

I don't know what to make of that. If X is the best way to achieve a goal
then X is the rational thing to do. The Monte Carlo Algorithm was invented
soon after the end of the second world war specifically to model how a
H-bomb worked, and it in effect flipped a coin millions of times. A
thermonuclear fireball is far too complex to model from first principles so
they generated random inputs for the position and momentum of particles and
then performed deterministic calculations from them and then found the
probability distribution. Without that the H-bomb would not exist. You can
argue if building a H-bomb is a rational goal or not but it you want to
figure out how to build one you've got to flip a coin many millions of

   John K Clark

No, it is not the rational thing to do. A rational agent has infinite
computing capacity and knowledge. A rational agent will know how to
simulate an H-bomb exactly without resorting to random approximations.

But that's impossible because (1) the quantum events he would simulate are inherently random and (2) he cannot know what information/energy will arrive from outside his past lightcone during the interval simulated. Such a concept of rationality can only be a useful approximations within a game such as chess.

It may well be a boundedly rational thing to do, although I'm not sure
this is even true.  I haven't studied bounded rationality theory in
great depth.

Of course all this is shining light on the concept of rationality,
which I personally think is rather suspect. Certainly, real people are
not rational - they have to get on with their lives.

I'd say they are rational, but that you have adopted an overly idealized defintion of 'rational'. But quite aside from quantum randomness, limited computational capacity, and signals from outside the past lightcone; people are 'irrational', or I would say 'extra-rational', because the values which they seek to satisfy are not and cannot be arrived at purely by ratiocination. These values are built-in by evolution, both biological and cultural. Rationality only serves to achieve a consilient subset of them.

Reason is, and ought only to be the slave of the passions, and can never pretend to any other office than to serve and obey them.
    --- David Hume

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