@xris,
I've been thinking about why I say the search for life in general and the search for intelligent life are somewhat different. Remember, that one of the arguments I advance in support of the idea for life in general in the universe involves the Universe's infinite multitude of stars and our normative position within, that is, orbiting a perfectly normal star in a perfectly normal part of a perfectly normal galaxy.
However, any argument that derives from infinities must necessarily provide for pretty much
any conclusion, especially the conclusion that
intelligent extraterrestrial life is prevalent. While some would characterize this as a fatal weakness of my argument, I believe there are several mitigating factors at work that fatally weaken this counterargument.
1. The exponential rarity of intelligent life on Earth seems to imply its exponential rarity elsewhere. There is only one confirmed truly intelligent species here, to wit, us, out of the many billions of species that have existed beforehand. That is to say that intelligent life is
much less likely to evolve than just life in general.
2. The part of the Universe we can see is
not infinite. It is, instead, a
finite amount of space, to wit, Sol's past light cone, or the light from elsewhere in the Universe that eventually radiates to Sol. Since I advance my argument only from within this context, especially the derivations about our cosmological normality, my own argument itself is proved invalid unless it disallows the infinity of totality, that is, it focuses instead on the finite "infinity" present in our past light cone.
3. My argument says that our existence is predicated on our cosmological normalcy. In other words, there are other normal stars out there, and among them
some likely have planets supporting life. Rationality, as I have pointed out, is a cosmological abnormality.
4. The only way we can prove
intelligent life exists is by contacting it. Well, so what? you might be asking, but here on Earth a being can only be proved intelligent by likewise intelligent contact. This implies that, per my argument, we can come to broad conclusions about life in general, but by and large only prokaryotic or simple eukaryotic forms; we cannot imply intelligence without intelligent contact.
5. If there is other intelligent life out there, it is most likely outside our light cone and therefore uncontactable and therefore my argument cannot say whether or not they exist.
6. Therefore, insofar as we can currently ascertain, it seems highly unlikely there is other intelligent life out there.