"The fundamental problem is whether natural science suffices to explain human beings."
Continuing discussion from: http://charltonteaching.blogspot.com/2011/10/natural-selection-as-metaphysical.html
Chastek's is an excellent framing of the discussion - with evolution by natural selection seen as merely a subtype of the general class of 'scientific' (non-divine, natural) explanations.
Science gets precision as a by-product of its metaphysical simplification - that which science leaves-out, it does not first disprove, it simply ignores and proceeds on that basis.
The consequent model of reality has no intrinsic validity (no matter how self-consistent that model may turn-out to be) because it is built on deliberately-simplified, and therefore presumably incomplete, foundations.
For the conclusions of science to be valid, would require a demonstration that the deliberate incompleteness of the foundations of science did not (?significantly) affect the validity of the model built upon them.
Interestingly, one of the ways that science has used to assume (without needing to demonstrate) its own completeness is to denigrate common sense, spontaneous knowledge, natural law, the consensus of human history etc.
If common sense is regarded as having zero validity, then the fact that aspects of common sense reality have been left-out of the scientific model is of no consequence.
If the consensus of history is ejected wholesale, this does not matter since it was, anyway, arbitrary.
Humans are (by this metaphysical account - it is not an empirical discovery) born into the world naked of mind and body, to be shaped by society - which itself has no intrinsic validity.
In a word: nihilism.