Darwin's Dangerous Idea - Evolution and the Meaning of Life

166 PRIMING DARWIN'S PUMP
quite strong that this is often the case, and not just in discussions of the
Anthropic Principle. Consider the related confusions that surround Darwinian
deduction in general. Darwin deduces that human beings must have evolved
from a common ancestor of the chimpanzee, or that all life must have arisen
from a single beginning, and some people, unaccountably, take these
deductions as claims that human beings are somehow a necessary product of
evolution, or that life is a necessary feature of our planet, but nothing of the
kind follows from Darwin's deductions properly construed. What must be the
case is not that we are here, but that since we are here, we evolved from
primates. Suppose John is a bachelor. Then he must be single, right? (That's a
truth of logic.) Poor John—he can never get married! The fallacy is obvious
in this example, and it is worth keeping it in the back of your mind as a
template to compare other arguments with.
Believers in any of the proposed strong versions of the Anthropic Principle
think they can deduce something wonderful and surprising from the
fact that we conscious observers are here—for instance, that in some sense
the universe exists for us, or perhaps that we exist so that the universe as a
whole can exist, or even that God created the universe the way He did so that
we would be possible. Construed in this way, these proposals are attempts to
restore Paley's Argument from Design, readdressing it to the Design of the
universe's most general laws of physics, not the particular constructions those
laws make possible. Here, once again, Darwinian coun-termoves are
available.
These are deep waters, and most of the discussions of the issues wallow in
technicalities, but the logical force of these Darwinian responses can be
brought out vividly by considering a much simpler case. First, I must introduce
you to the Game of Life, a nifty meme whose principal author is the
mathematician John Horton Conway. (I will be putting this valuable thinking
tool to several more uses, as we go along. This game does an excellent job of
taking in a complicated issue and reflecting back only the dead-simple
essence or skeleton of the issue, ready to be understood and appreciated.)
Life is played on a two-dimensional grid, such as a checkerboard, using
simple counters, such as pebbles or pennies—or one could go high-tech and
play it on a computer screen. It is not a game one plays to win; if it is a game
at all, it is solitaire. 4 The grid divides space into square cells, and each cell
4. This description of Life is adapted from an eariier exposition of mine (1991b). Martin
Gardner introduced the Game of Life to a wide audience in two of his "Mathematical
Games" columns in Scientific American, in October 1970 and February 1971. Poundstone
1985 is an excellent exploration of the game and its philosophical implications.
The Laws of the Game of Life 167
FIGURE 7.2
is either ON or OFF at each moment. (If it is ON, place a penny on the square;
if it is OFF, leave the square empty.) Notice in figure 7.2 that each cell has
eight neighbors: the four adjacent cells—north, south, east, and west—and
the four diagonals—northeast, southeast, southwest, and northwest.
Time in the Life world is discrete, not continuous; it advances in ticks, and
the state of the world changes between each two ticks according to the
following rule:
Life Physics: For each cell in the grid, count how many of its eight neighbors
are ON at the present instant. If the answer is exactly two, the cell stays
in its present state ( ON or OFF ) in the next instant. If the answer is exactly
three, the cell is ON in the next instant whatever its current state. Under all
other conditions, the cell is OFF.
That's it—that's the only rule of the game. You now know all there is to
know about how to play Life. The entire physics of the Life world is captured
in that single, unexceptioned law. Although this is the fundamental law of
the "physics" of the Life world, it helps at first to conceive this curious
physics in biological terms: think of cells going ON as births, cells going OFF
as deaths, and succeeding instants as generations. Either overcrowding (more
than three inhabited neighbors) or isolation (fewer than two inhabited
neighbors) leads to death. Consider a few simple cases.
In the configuration in figure 7.3, only cells d and / each have exactly
three neighbors ON, so they will be the only birth cells in the next generation.
Cells b and h each have only one neighbor ON, SO they die in the next
generation. Cell e has two neighbors ON, SO it stays on. Thus the next
"instant" will be the configuration shown in figure 7.4.