Subject: 
        [evol-psych] Darwin & Hume's moral sense
   Date: 
        Thu, 14 Feb 2002 08:30:04 -0600
   From: 
        "Larry Arnhart" 
     To: 
        




In summarizing his account of the moral sense in the last chapter of THE
DESCENT OF MAN, Darwin explains our experience of "ought" as expressing
a certain kind of feeling:  "Any instinct which is permanently stronger
or more enduring than another, gives rise to a feeling which we express
by saying that it ought to be obeyed."  Although many philosophers today
would say that this violates the is/ought dichotomy first stated by
David Hume, I think that Darwin's biological theory of morality as
rooted in moral feelings or sentiments was derived largely from his
reading of Hume (as well as Adam Smith).  Some of my reasoning is
developed in my book, DARWINIAN NATURAL RIGHT: THE BIOLOGICAL ETHICS OF
HUMAN NATURE (SUNY Press, 1998).
     The common interpretation of Hume as having separated "is" and
"ought" depends on only one paragraph in his TREATISE OF HUMAN NATURE. 
The textual context of this paragraph makes clear that Hume's claim is
that moral distinctions are derived not from pure reason alone but from
a moral sense.  The historical context makes clear that Hume is
restating Francis Hutcheson's criticisms of some early modern
rationalists who believed that moral distinctions could be derived from
abstract reasoning about structures in the universe that were completely
independent of human nature.  Far from denying that moral judgments are
judgments of fact, Hume claims that they are factual judgments about the
species-typical pattern of moral sentiments in specified circumstances.
     Hume compares moral judgments to judgments of secondary qualities
such as colors.  My judgment that this tomato is red is true if the
object is so constituted as to induce the impression of red in normally
sighted human beings viewing it under standard conditions.  Similarly,
my judgment that this person is morally praiseworthy is true if there
person's conduct is such as to induce the sentiment of approbation in
normal human beings under standard conditions.  Just as an object can
appear red to me when in fact it is not, so a person can appear
praiseworthy to me when in fact he is not.  The moral judgment whether
some conduct would give to a normal spectator under standard conditions
a moral sentiment of approbation is, Hume insists, "a plain matter of
fact."  The moral sentiment itself, however, is a feeling or passion
rooted in human nature that cannot be produced by reason alone.
     Hume's comparison of moral judgments and judgments of color is
apt.  We know that although there is variation in color vocabulary
across different languages, which reflects cultural variation, there is
a regularity in those vocabularies that manifests the way the human
visual system divides the spectrum of visible light into the principal
colors blue, green, yellow, and red.  This color spectrum is arbitrary
in an ultimately biological sense, because different visual systems
could have evolved.  But once it evolved in the human species, it could
not be radically altered by culture, although there can be some cultural
variation in the details of color vocabulary.  Similarly, there can be
some variation in our moral vocabularies across cultures, but there will
be a regularity in those moral vocabularies that reflects the regularity
in the moral emotions of normal people.  
     Of course, just as there are people born color-blind, so there
might be people born as potential psychopaths who do not feel the moral
emotions of normal people.  The case of primary psychopaths actually
reveals the fundamental importance of moral emotions.  Psychopaths do
not suffer from any deficit in their capacities for abstract reasoning,
and yet they lack a moral sense because they do not feel the moral
emotions of normal people.
     Edward Westermarck's account of incest avoidance shows that our
moral emotions of aversion to incest manifest the same  pattern of
natural regularity and cultural variability that one sees in color
vocabularies.  We are naturally inclined to feel sexual aversion to
those with whom we have been raised, and this aversion expresses itself
in customary and legal rules of incest avoidance.  Almost universally,
we will feel strong emotions of aversion towards sex between full
siblings or between parents and their children. Various lines of
evidence suggest that this is an epigenetic rule favored by natural
selection to avoid the deleterious effects of inbreeding.  But once we
move beyond the nuclear family, there can be great variation as to what
kind of matings are condemned as incest.  Like color vocabularies, there
is cultural variation, but there is also a natural regularity that
reflects our biological human nature.  
     Evolutionary psychologists could make important contributions to
our understanding of morality by following the pattern of Westermarck's
biological explanation of the incest taboo to explain other areas of our
moral experience.  Generally, however, they have not done this, because
they adhere to a rigid Kantian view of morality as expressing a
transcendent "ought" that must be separated from the empirical facts of
natural human desires.

Larry Arnhart

Department of Political Science
Northern Illinois University
DeKalb, Illinois 60115