Hal Finney wrote,
>There is still a very hard step here, going from the building blocks
>to self-replication. Until we have come up with some convincing way
>to bridge this gap I don't think we can say that scientific evidence
>suggests that life is likely to be common.
True. Likewise, until we have actual scientific evidence confirming how life originates, I don't think we can accurately evaluate the rarity of life (or the abundance of life) throughout the universe. Thank you for reminding me that we need to find empirically substantiated facts. We need to find out much more before drawing conclusions. The data about the comparative "uniqueness" of our solar system adds a bit to the Big Picture, but not enough to form reliable cosmic absolutes.