| The Improbability of God by Richard Dawkins
The following article is from Free Inquiry
magazine, Volume 18, Number 3.
Much of what people do is done in the name of God. Irishmen blow
each other up in his name. Arabs blow themselves up in his name. Imams and ayatollahs
oppress women in his name. Celibate popes and priests mess up people's sex lives in his
name. Jewish shohets cut live animals' throats in his name. The achievements of
religion in past history - bloody crusades, torturing inquisitions, mass-murdering
conquistadors, culture-destroying missionaries, legally enforced resistance to each new
piece of scientific truth until the last possible moment - are even more impressive. And
what has it all been in aid of? I believe it is becoming increasingly clear that the
answer is absolutely nothing at all. There is no reason for believing that any sort of
gods exist and quite good reason for believing that they do not exist and never have. It
has all been a gigantic waste of time and a waste of life. It would be a joke of cosmic
proportions if it weren't so tragic.
Why do people believe in God? For most people the answer is still
some version of the ancient Argument from Design. We look about us at the beauty and
intricacy of the world - at the aerodynamic sweep of a swallow's wing, at the delicacy of
flowers and of the butterflies that fertilize them, through a microscope at the teeming
life in every drop of pond water, through a telescope at the crown of a giant redwood
tree. We reflect on the electronic complexity and optical perfection of our own eyes that
do the looking. If we have any imagination, these things drive us to a sense of awe and
reverence. Moreover, we cannot fail to be struck by the obvious resemblance of living
organs to the carefully planned designs of human engineers. The argument was most famously
expressed in the watchmaker analogy of the eighteenth-century priest William Paley. Even
if you didn't know what a watch was, the obviously designed character of its cogs and
springs and of how they mesh together for a purpose would force you to conclude "that
the watch must have had a maker: that there must have existed, at some time, and at some
place or other, an artificer or artificers, who formed it for the purpose which we find it
actually to answer; who comprehended its construction, and designed its use." If this
is true of a comparatively simple watch, how much the more so is it true of the eye, ear,
kidney, elbow joint, brain? These beautiful, complex, intricate, and obviously
purpose-built structures must have had their own designer, their own watchmaker - God.
So ran Paley's argument, and it is an argument that nearly all
thoughtful and sensitive people discover for themselves at some stage in their childhood.
Throughout most of history it must have seemed utterly convincing, self-evidently true.
And yet, as the result of one of the most astonishing intellectual revolutions in history,
we now know that it is wrong, or at least superfluous. We now know that the order and
apparent purposefulness of the living world has come about through an entirely different
process, a process that works without the need for any designer and one that is a
consequence of basically very simple laws of physics. This is the process of evolution by
natural selection, discovered by Charles Darwin and, independently, by Alfred Russel
Wallace.
What do all objects that look as if they must have had a designer
have in common? The answer is statistical improbability. If we find a transparent pebble
washed into the shape of a crude lens by the sea, we do not conclude that it must have
been designed by an optician: the unaided laws of physics are capable of achieving this
result; it is not too improbable to have just "happened." But if we find an
elaborate compound lens, carefully corrected against spherical and chromatic aberration,
coated against glare, and with "Carl Zeiss" engraved on the rim, we know that it
could not have just happened by chance. If you take all the atoms of such a compound lens
and throw them together at random under the jostling influence of the ordinary laws of
physics in nature, it is theoretically possible that, by sheer luck, the atoms
would just happen to fall into the pattern of a Zeiss compound lens, and even that the
atoms round the rim should happen to fall in such a way that the name Carl Zeiss is etched
out. But the number of other ways in which the atoms could, with equal likelihood, have
fallen, is so hugely, vastly, immeasurably greater that we can completely discount the
chance hypothesis. Chance is out of the question as an explanation.
This is not a circular argument, by the way. It might seem to be
circular because, it could be said, any particular arrangement of atoms is, with
hindsight, very improbable. As has been said before, when a ball lands on a particular
blade of grass on the golf course, it would be foolish to exclaim: "Out of all the
billions of blades of grass that it could have fallen on, the ball actually fell
on this one. How amazingly, miraculously improbable!" The fallacy here, of course, is
that the ball had to land somewhere. We can only stand amazed at the improbability of the
actual event if we specify it a priori: for example, if a blindfolded man spins
himself round on the tee, hits the ball at random, and achieves a hole in one. That would
be truly amazing, because the target destination of the ball is specified in advance.
Of all the trillions of different ways of putting together the atoms
of a telescope, only a minority would actually work in some useful way. Only a tiny
minority would have Carl Zeiss engraved on them, or, indeed, any recognizable
words of any human language. The same goes for the parts of a watch: of all the billions
of possible ways of putting them together, only a tiny minority will tell the time or do
anything useful. And of course the same goes, a fortiori, for the parts of a
living body. Of all the trillions of trillions of ways of putting together the parts of a
body, only an infinitesimal minority would live, seek food, eat, and reproduce. True,
there are many different ways of being alive - at least ten million different ways if we
count the number of distinct species alive today - but, however many ways there may be of
being alive, it is certain that there are vastly more ways of being dead!
We can safely conclude that living bodies are billions of times too
complicated - too statistically improbable - to have come into being by sheer chance. How,
then, did they come into being? The answer is that chance enters into the story, but not a
single, monolithic act of chance. Instead, a whole series of tiny chance steps, each one
small enough to be a believable product of its predecessor, occurred one after the other
in sequence. These small steps of chance are caused by genetic mutations, random changes -
mistakes really - in the genetic material. They give rise to changes in the existing
bodily structure. Most of these changes are deleterious and lead to death. A minority of
them turn out to be slight improvements, leading to increased survival and reproduction.
By this process of natural selection, those random changes that turn out to be beneficial
eventually spread through the species and become the norm. The stage is now set for the
next small change in the evolutionary process. After, say, a thousand of these small
changes in series, each change providing the basis for the next, the end result has
become, by a process of accumulation, far too complex to have come about in a single act
of chance.
For instance, it is theoretically possible for an eye to spring into
being, in a single lucky step, from nothing: from bare skin, let's say. It is
theoretically possible in the sense that a recipe could be written out in the form of a
large number of mutations. If all these mutations happened simultaneously, a complete eye
could, indeed, spring from nothing. But although it is theoretically possible, it is in
practice inconceivable. The quantity of luck involved is much too large. The
"correct" recipe involves changes in a huge number of genes simultaneously. The
correct recipe is one particular combination of changes out of trillions of equally
probable combinations of chances. We can certainly rule out such a miraculous coincidence.
But it is perfectly plausible that the modern eye could have sprung from
something almost the same as the modern eye but not quite: a very slightly less elaborate
eye. By the same argument, this slightly less elaborate eye sprang from a slightly less
elaborate eye still, and so on. If you assume a sufficiently large number of
sufficiently small differences between each evolutionary stage and its predecessor,
you are bound to be able to derive a full, complex, working eye from bare skin. How many
intermediate stages are we allowed to postulate? That depends on how much time we have to
play with. Has there been enough time for eyes to evolve by little steps from nothing?
The fossils tell us that life has been evolving on Earth for more
than 3,000 million years. It is almost impossible for the human mind to grasp such an
immensity of time. We, naturally and mercifully, tend to see our own expected lifetime as
a fairly long time, but we can't expect to live even one century. It is 2,000 years since
Jesus lived, a time span long enough to blur the distinction between history and myth. Can
you imagine a million such periods laid end to end? Suppose we wanted to write the whole
history on a single long scroll. If we crammed all of Common Era history into one metre of
scroll, how long would the pre-Common Era part of the scroll, back to the start of
evolution, be? The answer is that the pre-Common Era part of the scroll would stretch from
Milan to Moscow. Think of the implications of this for the quantity of evolutionary change
that can be accommodated. All the domestic breeds of dogs - Pekingeses, poodles, spaniels,
Saint Bernards, and Chihuahuas - have come from wolves in a time span measured in hundreds
or at the most thousands of years: no more than two meters along the road from Milan to
Moscow. Think of the quantity of change involved in going from a wolf to a Pekingese; now
multiply that quantity of change by a million. When you look at it like that, it becomes
easy to believe that an eye could have evolved from no eye by small degrees.
It remains necessary to satisfy ourselves that every one of the
intermediates on the evolutionary route, say from bare skin to a modern eye, would have
been favored by natural selection; would have been an improvement over its predecessor in
the sequence or at least would have survived. It is no good proving to ourselves that
there is theoretically a chain of almost perceptibly different intermediates leading to an
eye if many of those intermediates would have died. It is sometimes argued that the parts
of an eye have to be all there together or the eye won't work at all. Half an eye, the
argument runs, is no better than no eye at all. You can't fly with half a wing; you can't
hear with half an ear. Therefore there can't have been a series of step-by-step
intermediates leading up to a modern eye, wing, or ear.
This type of argument is so naive that one can only wonder at the
subconscious motives for wanting to believe it. It is obviously not true that half an eye
is useless. Cataract sufferers who have had their lenses surgically removed cannot see
very well without glasses, but they are still much better off than people with no eyes at
all. Without a lens you can't focus a detailed image, but you can avoid bumping into
obstacles and you could detect the looming shadow of a predator.
As for the argument that you can't fly with only half a wing, it is
disproved by large numbers of very successful gliding animals, including mammals of many
different kinds, lizards, frogs, snakes, and squids. Many different kinds of tree-dwelling
animals have flaps of skin between their joints that really are fractional wings. If you
fall out of a tree, any skin flap or flattening of the body that increases your surface
area can save your life. And, however small or large your flaps may be, there must always
be a critical height such that, if you fall from a tree of that height, your life would
have been saved by just a little bit more surface area. Then, when your descendants have
evolved that extra surface area, their lives would be saved by just a bit more still if
they fell from trees of a slightly greater height. And so on by insensibly graded steps
until, hundreds of generations later, we arrive at full wings.
Eyes and wings cannot spring into existence in a single step. That
would be like having the almost infinite luck to hit upon the combination number that
opens a large bank vault. But if you spun the dials of the lock at random, and every time
you got a little bit closer to the lucky number the vault door creaked open another chink,
you would soon have the door open! Essentially, that is the secret of how evolution by
natural selection achieves what once seemed impossible. Things that cannot plausibly be
derived from very different predecessors can plausibly be derived from only
slightly different predecessors. Provided only that there is a sufficiently long series of
such slightly different predecessors, you can derive anything from anything else.
Evolution, then, is theoretically capable of doing the job
that, once upon a time, seemed to be the prerogative of God. But is there any evidence
that evolution actually has happened? The answer is yes; the evidence is overwhelming.
Millions of fossils are found in exactly the places and at exactly the depths that we
should expect if evolution had happened. Not a single fossil has ever been found in any
place where the evolution theory would not have expected it, although this could
very easily have happened: a fossil mammal in rocks so old that fishes have not yet
arrived, for instance, would be enough to disprove the evolution theory.
The patterns of distribution of living animals and plants on the
continents and islands of the world is exactly what would be expected if they had evolved
from common ancestors by slow, gradual degrees. The patterns of resemblance among animals
and plants is exactly what we should expect if some were close cousins, and others more
distant cousins to each other. The fact that the genetic code is the same in all living
creatures overwhelmingly suggests that all are descended from one single ancestor. The
evidence for evolution is so compelling that the only way to save the creation theory is
to assume that God deliberately planted enormous quantities of evidence to make it look
as if evolution had happened. In other words, the fossils, the geographical distribution
of animals, and so on, are all one gigantic confidence trick. Does anybody want to worship
a God capable of such trickery? It is surely far more reverent, as well as more
scientifically sensible, to take the evidence at face value. All living creatures are
cousins of one another, descended from one remote ancestor that lived more than 3,000
million years ago.
The Argument from Design, then, has been destroyed as a reason for
believing in a God. Are there any other arguments? Some people believe in God because of
what appears to them to be an inner revelation. Such revelations are not always edifying
but they undoubtedly feel real to the individual concerned. Many inhabitants of lunatic
asylums have an unshakable inner faith that they are Napoleon or, indeed, God himself.
There is no doubting the power of such convictions for those that have them, but this is
no reason for the rest of us to believe them. Indeed, since such beliefs are mutually
contradictory, we can't believe them all.
There is a little more that needs to be said. Evolution by natural
selection explains a lot, but it couldn't start from nothing. It couldn't have started
until there was some kind of rudimentary reproduction and heredity. Modern heredity is
based on the DNA code, which is itself too complicated to have sprung spontaneously into
being by a single act of chance. This seems to mean that there must have been some earlier
hereditary system, now disappeared, which was simple enough to have arisen by chance and
the laws of chemistry and which provided the medium in which a primitive form of
cumulative natural selection could get started. DNA was a later product of this earlier
cumulative selection. Before this original kind of natural selection, there was a period
when complex chemical compounds were built up from simpler ones and before that a period
when the chemical elements were built up from simpler elements, following the
well-understood laws of physics. Before that, everything was ultimately built up from pure
hydrogen in the immediate aftermath of the big bang, which initiated the universe.
There is a temptation to argue that, although God may not be needed
to explain the evolution of complex order once the universe, with its fundamental laws of
physics, had begun, we do need a God to explain the origin of all things. This idea
doesn't leave God with very much to do: just set off the big bang, then sit back and wait
for everything to happen. The physical chemist Peter Atkins, in his beautifully written
book The Creation, postulates a lazy God who strove to do as little as
possible in order to initiate everything. Atkins explains how each step in the history of
the universe followed, by simple physical law, from its predecessor. He thus pares down
the amount of work that the lazy creator would need to do and eventually concludes that he
would in fact have needed to do nothing at all!
The details of the early phase of the universe belong to the realm
of physics, whereas I am a biologist, more concerned with the later phases of the
evolution of complexity. For me, the important point is that, even if the physicist needs
to postulate an irreducible minimum that had to be present in the beginning, in order for
the universe to get started, that irreducible minimum is certainly extremely simple. By
definition, explanations that build on simple premises are more plausible and more
satisfying than explanations that have to postulate complex and statistically improbable
beginnings. And you can't get much more complex than an Almighty God!
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