What sort of argument is offered in support of (a)? It seems to me to be remarkable that there is life at all --- why should we believe that the probability of intelligent life on a given planet is more than, say, one in 10^100?
The simplest - but indirect - answer is just the Principle of Mediocrity. Astronomically, there doesn't appear to be any big way in which our planet is special. So why would we be special in this respect either?
The book goes through a lot of direct argument too. At least according to its summary of the literature, it seems relatively easy for life to originate. Once you've got life, evolution makes the emergence of intelligence at least seem somewhat likely.
Cheers,
Chris Auld Department of Economics University of Calgary [EMAIL PROTECTED]
-- Prof. Bryan Caplan Department of Economics George Mason University http://www.bcaplan.com [EMAIL PROTECTED]
"Infancy conforms to nobody: all conform to it, so that
one babe commonly makes four or five out of the adults
who prattle and play to it."--Ralph Waldo Emerson, "Self-Reliance"
