SERMON Professor Peter Lipton, Fellow of King’s College Cambridge
Sermon given at Matins and Sermon before the University, Kings College Chapel Cambridge, 28 th May 2006
Today's reading from the Hebrew Bible (2 Kings 2:9-15) tells part of the story of Elisha,
Elijah's disciple and successor. Although perhaps not as famous as his teacher, Elisha is
renowned for his miracle working, including the resurrection of a dead boy (4:32-7). Since
miracles are of particular philosophical interest, and I happen to be a philosopher, it is
miracles that I will discuss.
Philosophers are trouble-makers, and some have tried to make trouble for the very concept of
a miracle. To be a miracle, an event must be divinely caused, but that is not enough. It also
has to be dramatic. Just how dramatic will vary from person to person. A grandmother was
taking her little grandchild for a summer walk along the beach when a great wave arrived
from nowhere and swept the child out to sea. The grandmother fell to the ground and prayed,
imploring God to save the child. No sooner did she complete her prayer but another great
wave crashed onto the shore and deposited the child next to the grandmother, entirely
unharmed. The woman looked up to heaven, and said, 'He had a hat!’
Although it might not have been enough for the grandmother, the additional condition that it
typically added to the definition of a miracle is that the divine action must break a law of
nature. This makes some philosophers extremely nervous, since this seems to involve a
confusion. Human laws and moral laws can be broken, but what would it mean to break a law
of nature? The black swans in Australia do not break the law that all swans are white: they
just show that this isn't a law after all. Laws of nature may be misidentified, but not broken.
But suppose that a way can be found around this problem; say a way of making sense of the
idea that a law can have exceptions. A miracle will then be one of these, caused by God. Now,
however, philosophers create another difficulty, not over what it means to be a miracle, but
over how we can ever have a good reason to believe that one has occurred. For there is a
mesmerising argument due to the great 18th century Scottish sceptic David Hume, according
to which testimony to a miracle should never be believed.
Faced with testimony of any sort, Hume presses us to apportion our belief to the evidence. If I
tell you that this afternoon the Chapel Shop will be giving away the pieces of our stained
glass windows, you need to decide which is more probable: that they are really going to break
up this magnificent medieval glass or that, whether through confusion or malice, I have
misled you. And that judgement of relative probability should be based on the balance of
evidence, of likely Chapel Shop practice on the one hand, and of my competence and honesty
on the other.
Hume's advice about the appraisal of testimony is entirely general, but he goes on to make a
cunning point about the particular case that interests us: the case of testimony to a miracle.
Hume's point is not that a miracle is impossible in principle, but that that we can never be in a
position rationally to believe in one on the basis of testimony. Since a miracle must be a
violation of the laws of nature to qualify as such, a miracle must also be a maximally unlikely
event. So it will always be more probable that the testimony was mistaken than that the
miracle occurred. As Hume puts it, you shouldn't believe in a miracle on the basis of
testimony, unless the falsity of the testimony would require a greater miracle.
The difficulties first in saying what a miracle would be and second in seeing how we could
ever be in a position rationally to affirm that one has occurred both relate to what is these
days a hot topic: intelligent design. This controversy has strong political and cultural
components. As an American living in Britain, I cannot but wonder why intelligent design is
so much more of an issue in the States than it is here (though that is not why I came over).
Part of the answer must have to do with a separation of church and state enshrined in the US
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SERMON Professor Peter Lipton, Fellow of King’s College Cambridge
constitution that has pushed American creationists to present an argument from design as
science, in an attempt to make it legal to teach creationism in the States' state schools.
But there is also an interesting philosophical angle to the intelligent design movement. The
proponents of intelligent design seem to have taken Hume's critique of miracles on board.
They see the need to come up with a situation where it is the absence of divine action that
would require the greater miracle. Thus they argue that for complex biological organs to have
evolved through a Darwinian mechanism of random mutation and selective retention would
require a coincidence of mutations so incredibly unlikely as to be effectively impossible. In
such a situation, the probability of the alternative hypothesis of an intelligent designer must be
substantially greater. What the proponents of intelligent design would like to say is that, when
it comes to the complex organs of plants and animals, it would be a miracle if God wasn't
responsible.
Many scientists are extremely hostile to intelligent design, including many scientists with
serious religious commitments. I share the hostility, but I don't approve of all the strategies of
attack. It is not effective simply to dismiss intelligent design on the grounds that an appeal to
supernatural intelligence is by definition unscientific. What matters most about the claim is
not whether it is scientific, but whether it is warranted. Nor is it advisable simply to assert that
intelligent design is stupid: one should reveal the weaknesses of the argument.
Many of these weaknesses are familiar. Even if the argument gave a reason for believing that
extra-terrestrial intelligence played a role in the development of life on earth, that is no
argument for the existence of God as opposed to the existence of powerful aliens. Indeed the
strategy of inferring what a designing intelligence is like from the sometimes horrific facts of
life on earth runs a very considerable danger of proving the wrong thing for those who wish to
end up with a designer who is all good and all powerful.
Darwin undermined the older argument from design, by showing how an unintelligent
mechanism of evolution by natural selection could generate organisms well-suited to their
environments. The proponents of intelligent design are attempting to strike back, by arguing
that Darwinian mechanism would require impossibly unlikely combinations of mutations in
order to generate complex organs (an objection that Darwin himself already considered). Here
we Darwinians must emphasise just how powerful, subtle and surprising the output of natural
selection may be. For example, as the evolutionary biologists Stephen Jay Gould and Richard
Lewontin have emphasised, natural selection doesn't just generate adaptations: it also
generates by-products, which they called 'spandrels', that may themselves have wonderful
structure and may themselves suggest design.
One of the analogies Gould and Lewontin use is, fittingly enough, King's College Chapel.
Look up and admire the fabulous ceiling. Notice in particular the beautiful necklace of
diamond-shaped structures that forms its spine, with massive stone bosses hanging in the
centre of each diamond. It is almost as if the ceiling were designed around that beautiful
central geometrical feature. Yet as Gould and Lewontin observe, that is not likely. Those
diamond shapes are not the point of the ceiling design, but rather a byproduct of the fan vault
structure that holds everything up. The fan vaulting is the point, and once the builders commit
to that, they are stuck with those diamond shaped gaps (which they may then decide to fill
with decorative but structurally irrelevant bosses).
Spandrels illustrate how complex structures may evolve by natural selection even if they perform no
function. Complex organs did not evolve in one go: that is indeed too unlikely. They came rather from
simpler structures, which themselves may have been spandrels or organs with quite different functions
from those their successors possess. An elaborate wing may have come from a much simpler limb; a
sophisticated eye may have come from a much cruder organ that could only distinguish day from
night. A stepwise process of development involving variation in function and environment may yield
an end product of exquisite complexity, requiring neither intelligent design nor miracle.
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