Interesting read. To me it seems simple. The universal laws of physics applied to planet formation produce life. We have the empirical evidence in abundance. It is here on Earth. And we have empirical evidence of the building blocks of life in far flung objects such as comets. The alternative is that life is 'special' or magical. Good on you if you believe that, and I mean that sincerely - life's tough enough as it is being a germ on a rock out in the vastness of space.
It's very hard to get beyond our early cultural brainwashing that life is somehow miraculous, rather than a 'proven' expression of the ordering of matter from the chaos of starbirth. When we spectroscopically detect an exotic new compound in a distant star system, do we say, well that is the only place in the Universe that this compound exists, until we get indisputable empirical data to say otherwise?
Life elsewhere in the Universe becomes a reasonable assumption at the very least for similar melting pots, not speculation. And that is only for life as we know it. The burden of proof is on the naysayers to find evidence that life is magical after all, or that the Solar System (or Earth) is somehow unique in all the Universe, or that the universal laws that produce life apply to only our small corner of the Universe. The proof required would be extraordinary because we already have the empirical evidence. Fence-sitters... well they're in denial both ways.
In practical terms we may never detect life outside our own Solar System (or detect it to the satisfaction of everyone!), but we can be pretty certain it exists. We are the proof.
Cheers -
PS...
Maybe we should be looking for dark life, seeing as dark matter & energy dominate the Universe...
