The fallacy of Dennett's argument also undermines his other
imperialist hope--that the universal acid of natural selection
might reduce human cultural change to the Darwinian algorithm as
well. Dennett, following Dawkins once again, tries to identify
human thoughts and actions as "memes," thus viewing them as units
that are subject to a form of selection analogeous to natural
selection of genes. Cultural change, working by memetic
selection, then becomes as algorithmic as biological change
operating by natural selection on genes--thus uniting the
evolution of organisms and thoughts under a single ultra-
Darwinian rubric:
"According to Darwin's dangerous idea...not only all your
children and your children's children, but all of your
brainchildren's brainchildren must grow from the common stock of
Design elements, genes and memes...Life and all its glories are
thus united under a single perspective."
But, as Dennett himself correctly and repeatedly emphasizes, the
generality of an algorithm depends upon "substrate neutrality."
That is, the various materials (substrates) subject to the
mechanism (natural selection in this case) must all permit the
mechanism to work in the same effective manner. If one kind of
substrate tweaks the mechanism to operate differently (or, even
worse, not to work at all), then the algorithm fails. To choose
a somewhat silly example that actually played an important role
in recent American foreign policy, the cold war "domino theory"
held that communism must be stopped everywhere because if one
country turned red, then others would do so as well, for
countries are like dominos standing on their sides and placed one
behind the other--so that the toppling of one must propagate down
the entire line to topple all. Now if you devised a general
formula (algorithm) to describe the necessary propagation of such
toppling, and wanted to cite the algorithm as a general rule for
all systems made of a series of separate objects, then the
generality of your algorithm would depend upon substrate
neutrality--that is, upon the algorithm's common working,
regardless of substrate (similarly for dominos and nations in
this case). The domino theory failed because differences in
substrate affect the outcome, and such differences can even
derail the operations of the algorithm. Dominos must topple, but
the second nation in a line might brace itself, stay straight
upon impact, and therefore fail to propagate the collapse.
Natural selection does not enjoy this necessary substrate
neutrality. As the great evolutionist R. A. Fisher showed many
years ago in the founding document of modern Darwinism (The
Generical Theory of Natural Selection, 1930), natural selection
requires mendelian inheritance to be effective. Genetic
evolution works upon such a substrate and can therefore be
Darwinian. Cultural (or memetic) change manifestly operates on
the radically different substrate of Lamarckian inheritance, or
the passage of acquired characters to subsequent generations.
Whatever we invent in our lifetimes, we can pass on to our
children by our writing and teaching. Evolutionists have long
understood that Darwinism cannot operate effectively in systems
of Lamarkian inheritance--for Lamarkian change has such a clear
direction and permits evolution to proceed so rapidly, that the
much slower process of natural selection shrinks to
insignificance before the Lamarckian juggernaut.
The crucial difference between biological and cultural evolution
also undermines the self-proclaimed revolutionary pretensions of
a much publicised doctrine--evolutionary psychology--that it
would be quite useful if proponents would trade their propensity
for cultism and ultra-Darwinian fealty for a healthy dose of
modesty.
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He goes on about general principles that apply to both memetics
and evolutionary psychology, which I'm sure everyone will find
something to disagree with. I found a lot, but I recommend the
article because it tells me what arguments memetics will have
to address and defend itself against.
Grant