Because complexity does things, and in order to do things, you need
complexity, and you have to do things in order to survive and reproduce.
Relevant to this debate is the Ancestor ALife program. It is relevant
because it is known, absolutely, what the laws of physics were. They
did not include any mysterious forces. The run began with a single
self-reproducing and random-error-making string of code called the
"Ancestor", 80 characters long. Soon the Ancestor was replaced by a
hardier piece of code 79 characters long. (No artificial drive towards
complexity here, folks - the short pieces of code survived better
because they took less time to execute!) Then parasites evolved which
could be much shorter by "hijacking" the reproductive process of other
parasites. Then hyper-parasites that preyed on the parasites. Then
defenses against parasites and hyper-parasites. And so on and so on...
I don't believe that multi-cellular life evolved at any point, although
there was a point where two pieces of code would cooperate, which was
certainly a start. The point is that you have to do things to survive,
and you have to have complexity to do things.
No mysterious force has been shown to be necessary. Please try again.
--
sentience@pobox.com Eliezer S. Yudkowsky
http://tezcat.com/~eliezer/singularity.html
http://tezcat.com/~eliezer/algernon.html
Disclaimer: Unless otherwise specified, I'm not telling you
everything I think I know.