For those who might misinterpret my prior comments on Darwinism here's a clarification. The philosophy of Darwinism leads many people to use the word "paradox" to describe the lack of alien visitors. They all "know" that the evolution of sentient life is easy, so facile, that the Milky Way "must be" teaming with intelligent life. Therefore the lack of alien visitors to Earth is a paradox.
So here's the real science. There is no evidence that any aliens have ever visited our solar system. There is no evidence of artificial constructions in any solar system, star cluster, or interstellar location in the Milky Way. There is no evidence of any artificial construction in any galaxy we can see. There is no SETI signal, there is nothing.
The overall statistics of these observations lead to the following conclusion: the evolution of sentient space faring species is so rare that we might be the only one in the entire universe. The implications for Darwinism are devastating. While the evolution of bacteria might be trivial, and every solar system in the entire universe might contain primitive life, the evolution of intelligent life appears to be nearly impossible.
For over 10 billion years our Milky Way has been easily capable of supporting space faring explorers. Robotic spacecraft could explore the entire galaxy in about 100 million years. If they aren't here yet this means they waited at least 99% of the life of the galaxy before starting. Why did they wait? Statistically it's possible that we are the first, or one of the first, and nobody has been around long enough to explore the entire galaxy: statistically possible, and highly improbable. Either every single species has an impediment to building robotic exploration craft (remember it only takes one) or there aren't any.
For 10 billion years no extra-galactic species has constructed an object visible from Earth. Perhaps such structures are impossible. I doubt it. This is evidence that there are no aliens in other galaxies.
I claim there aren't any aliens anywhere in the entire universe, we are alone, and there is no evidence to the contrary. Many people have speculations, deeply held beliefs about Darwinism, Drake equations, planetary search data, ... but in the end these speculations are irrelevant. Visual observation is all that counts.
So the implications for Darwinism are this, the rate of evolution of intelligent space faring species is about once per universe per 13 billion years. It appears there are millions or billions of planets/galaxy capable of supporting an evolving ecosystem. So for any given planet in the entire universe the chance of evolution of intelligent life is about 100,000,000,000,000,000,000 to 1.
We didn't beat the odds, we just had the winning lottery ticket. If you bought 100 million lottery tickets you would not be surprised to find that one of them had the winning numbers. Out of billions of planets ours held the winning ticket in the Darwinian lottery.