David has reminded us many times here of how extraordinarily difficult it is for life to get started. His view is that it is, in principle, impossible and that, accordingly, science will NEVER be able to describe with certainty how it came about. To base a metaphysic on something so contingent seems unwise, particularly as this scenario may well come to pass within the lifetimes of everyone here writing. - I think this discussion by Paul Davies indicates not in our lifetimes, with 60 years of futilee effort behind us. Especially note his comment in the Origin of Life section on the enormous complexity of the simplist cell form. - http://physicsworld.com/cws/article/print/39669