Again, I would suggest reading the Rare Earth book. I am not good at
presenting what the book presents so well.

The authors are very up front that they are looking for real estate in the
universe that can produce life like ours. The likelihood of different
sorts of life produced on some completely different model is beyond the
scope of their discussion.

They are not saying that the Earth is the only planet around with plate
tectonics ... just the only one we know of and probably the only one in
our solar system.  They are basing their discussion on life like ours.
Life based on some other model is beyond the scope of their book.

Again, I say, it is easy to tear apart my few disconnected statements
about the theory.  Try reading the book and see if it can be discounted so
easily.
--

        Tom Hula
        Victor S. Barnes Company
        616.361.7351  x173