Natural law theory:
 or “the law of (human) nature” – the proposition that
we can use reason to analyze human nature and
deduce binding rules of moral conduct for all people
at all times, in all cultures and circumstances
 as opposed to “positive” or “man-made law” which
varies from time to time, place to place, and culture
to culture
 natural law philosophers
speak of “what we can’t not
know,” or “a universal law of right and wrong action,
carved on the human heart.” (cf. Gn 1; Jer 31:33)
 medieval philosophers used two words for
conscience, not just one, reflecting a real
difference between two aspects of the mind.
 Conscientia is the application of principles
from the universal basic moral law; it is here that
we can can err or disagree.
 Synderesis is the inner awareness of
universal moral principles – “what we can’t not
know” – and it cannot err
(though we can deny it exists).
 Research supports the assertion
that, although there have been differences in the moral codes of
human civilizations at different times and places, the really
striking thing it how very similar they are, as if there really is a
moral sense “carved on the human heart”. And there are other
human “universals” (e.g. grammar & the acquisition of
language) which suggest we really are governed by a “law of
human nature”
C.S. Lewis: “Mere Christianity”
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When people quarrel (“I was here first;” “Leave him
alone, he isn’t hurting anyone”), they speak as though
we aren’t merely personally offended by the other’s
actions, but that the other is wrong; i.e. that there is
some standard of behaviour everyone knows about
and should follow
o Human quarreling (trying to show that the other is
wrong) makes no sense unless there really is Right
and Wrong
o Usually we don’t deny such a standard exists, but
instead try to argue that in our special
circumstances we aren’t obliged to follow it; i.e. we
look for an excuse
This “Rule or Law about Right and Wrong” is what we
mean by “Natural Law”, or perhaps better, “The Law of
Human Nature,” and has been understood by all peoples in all ages
o Differences in morality between cultures and periods of history are relatively
minor; what is more striking is how similar the various moralities are
o To imagine a world in which morality is really different is like trying to
imagine a land in which people are praised for breaking promises, or running
away in battle – we can’t do it
 E.g. We have different understandings about whom we should treat
unselfishly – whether family and friends only, or countrymen too, or
everyone – but no one advocates or admires selfishness
o Even people who try to say there is no such “Law” appeal to it when you try
to treat them unfairly
Illustrations & Objections: WHO decides what is “natural”? And HOW?
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This “Natural Law” can’t be a mere “herd instinct” telling us to treat others well for the
sake of all
o Suppose you hear a cry for help from someone in danger. You probably feel two
“instincts”: the desire to help (herd instinct), and the desire to stay out of danger
(an instinct for self-preservation). Something else tells you that helping the
person in danger is more important, and the right thing to do, even if you don’t
want to do it.
Neither is morality a matter of mere “social convention,” or something put into us by
education, as if all we learn from parents or teachers is mere human convention – e.g.
driving on the right: we could just as easily have been taught to drive on the left (in some
countries they do), and that would not be wrong
o We also learn the times tables at school, but no one argues they are merely
conventional
 There are some things, like math, which are real truths – morality is this
kind of truth
 E.g. most people would argue that typical moral behaviour in Canada is
better or “truer” than that of the Nazis, or of Saddam Hussein – how can you
argue this way if there is not some real standard of moral behaviour?
Nor is morality a matter of doing merely what is useful to us, or convenient, or that “pays”
o The person who trips me by accident, and the one who does it on purpose, are both
equally inconvenient to me, but I blame only the latter, not the former: I am
measuring their behaviour by another standard
Nor is morality merely a matter of doing what is “good for society”
o E.g.
 “Why should I be unselfish?”
 “Because it’s good for society.”
 “Why should I care what’s good for society?”
 “Because you ought to be unselfish.”
 This is arguing “in a circle” which brings us right back to where we
started
o i.e. individual morality
Lewis goes on to argue that this “Natural Law” ...
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strongly challenges a determinist or materialist view of the
universe, and
supports the idea of a divine intelligence directing all things.