It kind of disturbs me to see people here saying "Why should we care what the Pope says about science", because it demonstrates a level of naiveté I didn't expect in these forums. Let's divide this up into secular and religious reasoning about "Why should we care?":
Secular
The Pope is literally a head of state; as a result, the Vatican has diplomatic relations with virtually every country in the world, and there are very few leaders that wouldn't receive the Pope (or his envoy) and meet with him. This kind of access to world leadership alone represents power; added to that is the kind of public relations clout and media coverage the Pope "enjoys" world-wide... and the degree of influence he has over the constituent populations in various countries. These aspects of the Papal office mean that he has power and influence with the rest of the world out of proportion to his direct religious following. (A not-insignificant power base by itself, I might add.)
Secondly, the idea that an opinion offered by someone on science who is not a scientist is irrelevant is self-contradictory. Sagan knew that the perception of the non-scientific community concerning science was (and is)
ABSOLUTELY CRITICAL to the scientific community. In other words "Joe Schmo and Jane Doe's" opinion of science can have a direct and relevant impact to the amount of funding and support that science enjoys - both directly and indirectly.
In fact, I'll make the claim that the controversy surrounding ID and education exists
strictly because the opinion of the "common person" concerning science matters. So suggesting that the opinion of a highly public, well recognized and influential figure like the Pope should be irrelevant is merely wishful thinking at best; at worst, it could be considered elitist arrogance.
Religious
The Pope isn't merely a religious figure; he is the
key religious figure for 1.1 billion Catholics, and - on a world-wide basis - one of the very few easily identifiable religious leaders in existence for Christianity. (And at 2.1 billion adherents, Christianity is the largest religion on the planet.) There are other Christian leaders of note, but as far as the world is concerned, the Pope pretty much speaks for Christianity - no matter how much that galls other Christian leaders.
So when the leader of the largest religious sect in the world (a sect that represents more than half of the worlds adherents in that religion and is also the de facto religious leader for the overall religion) speaks about anything - including and especially science - it's important.
If you dismiss the current comments by the Vatican's astronomer as irrelevant (And I'd like to see the logic behind dismissing his secular degrees and experience!) and if you dismiss JP II's comments concerning evolution and the church, you should consider what the impact would be if Coyne and JP had come out with the
reverse position. What if Coyne had said "ID should be taught as science in schools", or if JP had said "Evolution is merely a theory and should be ignored by all true Christians"?
The Pope (and the Vatican, and the Catholic Church) are the proverbial 800 lb Gorilla. You can choose to deplore it's existence, but the gorilla's still there. Be happy it's on your side.
