Of course I can only be as certain as the evidence we have. I also know that our understanding will probably evolve and change and we learn new information.
As for chance? Well, for every Earth (only one we know of) there are (as far as we know) billions of dead planets. After billions and billions of dead planets I'm perfectly will to accept that one with life is just chance.
That's not the only chance though. It's a chance within a chance within so many other chances over many, many years, from the moment the Big Bang happened.
For sure our knowledge will grow, but I am not so sure if this will apply to our understanding. Yet the more we know, the more we seem we don't know!
Hey thanks for letting me indulge in this thread, I was hoping to test my thoughts and learn something new (I did) :)
As for chance? Well, for every Earth (only one we know of) there are (as far as we know) billions of dead planets. After billions and billions of dead planets I'm perfectly will to accept that one with life is just chance.