You can generate arbitrarily low probabilities for anything by stacking arbitrary fractions. If evolution has no goal, then the absence of radio loud civilizations does not demand explanation, it is only paradoxical if you implicitly believe that intelligence plus technology is a natural attractor state.
Yes, agreed. Furthermore, high tech tool makers not being a goal of evolution is certain, not merely a supposition, there's no anthropomorphic force driving life in that direction. The natural attractor states of evolution can safely be assumed to be the niches evolution has repeatedly discovered and recreated on Earth numerous times, the cases of convergent evolution. If we were digging up fossils of technology created a hundred million years ago by a high tech species of birds or something, and more from another period from yet another totally different lineage, that would substantially change the math. But all the evidence on Earth points to a species like ours being a very rare thing for evolution to create.
Agree. And also: The universe contains multiple substrates, degrees of freedom, organizational proprties etc that could support advanced intelligence while being effectively totally invisible to a species/civilization like ours.
Absolutely. The advantages provided by advanced intelligence matter a lot less when when technology is still primitive, and during that period an intelligent species is likely to be quite vulnerable. At least, we were.
