“‘Moreover,’ added Arcade, ‘I freely acknowledge that it is almost impossible systematically to constitute a natural moral law.  Nature has no principles.  She furnishes us with no reason to believe that human life is to be respected.  Nature, in her indifference, makes no distinction between good and evil.’”  -- Anatole France, The Revolt of the Angels

There are two things to understand about this view:  (1) why it seems so obviously true to contemporary man, and (2) why it is false.

The problem is that several centuries ago, we tore out the teleological guts from our conception of nature.  If you no longer recognize pattern and significance in what happens, then “nature” can mean nothing to you except that stuff happens.  Since some of the stuff that happens is bad stuff, you inevitably conclude that nature is indifferent to good and evil.  It is a perfect example of how mistaken ideas enjoy a double life.  First we assume them; then we forget that we have assumed them; finally we dig them up again and shout “See what I’ve discovered!”

Can we stuff the teleological guts back in?  Sure.  To vary the metaphor, all we have to do is stop turning our eyes away from what nature is actually like.  What would we notice if we did?

One thing we would notice that nature is full of developmental arrows:  Go This Way.  Acorns turn into oaks; oaks produce acorns but they do not turn into them.  Babies turn into adults; adults do not run backwards and finally re-enter the womb.  The point isn’t that nothing ever interferes with the course of development, for some children do fail to thrive, and some adults lose their capacities.  Rather the point is that there is a course of development.  For natural potentialities to unfold is naturally good; for them to be thwarted is naturally bad.

Another thing we would notice is that nature is full of purposes.  Purposes exist in one way in the mind, in another way in things, and in yet another way in the mind of God.  Let us consider how they exist in things.  We don’t have to read God’s mind to know that hearts are for circulating blood; but if that is so, then a good heart is one that pumps well, a bad one is one that pumps badly, and we ought to help bad hearts pump better.  So nature is not indifferent to good and bad that way either.

Still another is that for beings like us, these purposes are coupled with meanings.  Whenever I give myself sexually, I am doing something that cannot help but mean the possibility of new life.  Someone might object "That's not true.  The chance of new life isn't a meaning of sex, at least not for me, because I don't want it.  I even take steps to prevent it."  I'm sorry, but what you intend subjectively can't change what your act means objectively.  To join in one flesh is to say, "I give myself to you in all that this act means," even if my mouth shapes the words, "It means nothing."

And have you noticed Arcade’s chief trick – that he does not consider the moral intellect natural?  But man is a rational being, and the first principles of practical reason are inscribed upon the tablets of his heart.  If it were not natural for us to reason morally – then how could it even occur to us to criticize nature for not being moral enough?