Of all the millions of unique and, with hindsight, equally improbable, positions of the combination lock, only one opens the lock. Similarly, of all the millions of unique and, with hindsight, equally improbable arrangements of a heap of junk, only one (or very few) will fly. The uniqueness of the arrangement that flies, or that opens the safe, is nothing to do with hindsight. It is specified in advance. The lock-manufacturer fixed the combination, and he has told the bank manager. The ability to fly is a property of an airliner that we specify in advance.
Given that chance is ruled out for sufficient levels of improbability, we know of only two processes that can generate specified improbability. They are intelligent design and natural selection, and only the latter is capable of serving as an ultimate explanation. It generates specified improbability from a starting point of great simplicity. Intelligent design can’t do that, because the designer must itself be an entity at an extremely high level of specified improbability. Whereas the specification of the Boeing 747 is that it must be able to fly, the specification of the ‘intelligent designer’ is that it must be able to design. And intelligent design cannot be the ultimate explanation for anything, for it begs the question of its own origin.
From the lowlands of primeval simplicity, natural selection gradually and steadily ramps its way up the gentle slopes of Mount Improbable until, after sufficient geological time, the end product of evolution is an object such as an eye or a heart – something of such an elevated level of specified improbability that no sane person could attribute it to random chance. The single most unfortunate misunderstanding of Darwinism is that it is a theory of chance; the misunderstanding presumably stems from the fact that mutation is random.*8 But natural selection is anything but random. To escape from chance is the primary accomplishment that any theory of life must aspire to. Obviously, if natural selection were a theory of random chance, it could not be right. Darwinian natural selection is the non-random survival of randomly varying coded instructions for building bodies.
Some engineers even use explicitly Darwinian methods in order to optimize systems. They escalate performance from poor beginnings up a ramp of improvement to something approaching an optimum. Something like this process may be true of all engineers, even if they don’t think of it as explicitly Darwinian. The engineer’s wastepaper basket holds the ‘mutant’ designs he discarded before putting them to the test. Some designs don’t even make it onto paper but are discarded in the engineer’s head. I have no need to pursue the question of whether Darwinian natural selection is a good or helpful model for what goes on in the brain of a creative engineer or artist; constructive creative work – by engineers or artists, or indeed anybody – may or may not plausibly represent a form of Darwinism. The fundamental point remains that all specified complexity must ultimately rise from simplicity by some kind of escalatory process.
If we ever discover evidence that some aspect of life on Earth is so complex that it must have been intelligently designed, scientists will face with equanimity – and doubtless some excitement – the possibility that it was designed by an extraterrestrial intelligence. The molecular biologist Francis Crick, together with his colleague Leslie Orgel, made such a suggestion (I suspect, tongue in cheek) in proposing the theory of directed panspermia. According to Orgel and Crick’s idea, extraterrestrial designers deliberately seeded Earth with bacterial life.*9 But the important point is that the designers were themselves the end product of some extraterrestrial version of Darwinian natural selection. The supernatural explanation fails to explain because it ducks the responsibility to explain itself.
Creationists who disguise themselves as ‘intelligent-design theorists’ have only one argument, and it goes like this:
1. The eye (the articulation of the mammalian jaw, the bacterial flagellum, the elbow joint of the lesser spotted weasel frog – which you have never heard of and don’t have time to look up before you seem to a lay audience to have lost the argument) is irreducibly complex.
2. Therefore it cannot have evolved by gradual degrees.
3. Therefore it must have been designed.
No supporting evidence is ever offered for step 1, the allegation of irreducible complexity. I have sometimes referred to it as the argument from personal incredulity. It is always offered as a negative argument: theory A is alleged to fail in some respect, so we have to default to theory B, without even asking whether theory B might be deficient in the very same respect.
One legitimate response of biologists to the argument from personal incredulity is to attack step 2: look carefully at the examples proposed and show that they either did, or could, easily evolve by gradual degrees. Darwin did this for the eye. Later paleontologists did it for the articulation of the mammalian jaw. Modern biochemists have done it for the bacterial flagellum.
But the message of this essay is that, strictly speaking, we needn’t bother to dispute steps 1 and 2. Even if they were ever accepted, step 3 remains irretrievably invalid. If incontrovertible evidence of intelligent design were ever discovered in, say, the organization of the bacterial cell – if we found evidence as strong as a manufacturer’s signature written in unmistakable characters of DNA – this could only be evidence of a designer that was itself the product of natural selection or of some other as yet unknown escalatory process. If such evidence were found, our minds should immediately start working along the lines of Crick’s directed panspermia, not a supernatural designer. Whatever else irreducible complexity might demonstrate, the one thing it cannot appeal to in ultimate explanation is something else that is irreducibly complex. Either you accept the argument from improbability, in which case it disproves the existence of ultimate designers. Or you don’t accept it, in which case any attempt to deploy it against evolution is inconsistent if not dishonest. You cannot have it both ways.
AFTERWORD
Many theologians pathetically try to have it both ways through a piece of brazen assertion. By fiat they assert that their creator god is not himself complex and improbable, but simple. We know he is simple because eminent theologians like Thomas Aquinas say he is simple! Was there ever evasion more transparently evasive than this? Not only must any creator worthy of the name have the computational power to conceive the quantum physics of fundamental particles, the relativistic physics of gravity, the nuclear physics of stars and the chemistry of life. He also, at least in the case of Aquinas’ God, has enough bandwidth left over to listen to the prayers and forgive – or not, according to taste – the sins of sentient beings all over his created universe. Simple?
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*1 This is my contribution to another book edited by John Brockman, this time in 2006, entitled Intelligent Thought: science versus the Intelligent Design movement.
*2 This dishonesty frequently goes unnoticed. The intelligent design ‘theorist’ (theorist is too flattering a word) talks as though it’s a minor detail whether the designer is God or an extraterrestrial alien. In fact the difference is huge, as this essay will show.
*3 Although it is strictly synonymous, I would now prefer to say ‘Which puts it well into the range that we would classify as impossible.’ Better still, ‘for all practical purposes impossible’. When we are dealing with such huge numbers, ‘possible’, ‘impossible’ and ‘practical purposes’ have to be understood in impractical ways.
*4 Eucaryotic cells are what we consist of – and by ‘we’ I mean all of life except bacteria and archaea. They are characterized by possession of a membrane-bound nucleus containing DNA, and ‘organelles’ such as mitochondria which, we now know, originated as symbiotic bacteria, and which still reproduce autonomously within the cell with their own DNA. Ridley is presumably right to regard such symbiotic unions as very improbable, lucky events. Nevertheless, there were two of them at least: one when green bacteria joined the club and provided – as chloroplasts – the photosynthetic know-how that all plants still use; and again when the ancestors of mitochondria came into the fold. Lynn Margulis (wh
o had a track record of being right as well as wrong) believed there were yet more such momentous unions.
*5 Life forms of our present level don’t have the technology adequate to traverse immense distances. So the barrier will have to be penetrated by beings with far superior technology and science.
*6 To revert to an earlier footnote (see this page), this may be why nobody before Darwin and Wallace, not even the greatest thinkers such as Aristotle or Newton, tumbled to natural selection.
*7 My friend the philosopher Daniel Dennett argues forcefully, for example in From Bacteria to Bach and Back, that we should drop the word ‘illusion’ and simply use ‘design’ for what natural selection does. I see his point, but to follow him would obscure mine. In his terms we could say natural selection designs, and among the entities that it designs are those, such as brains, which are themselves capable of designing. I’m not going to get worked up about the semantics.
*8 Actually that may be too charitable an explanation of the misunderstanding. It could stem from imaginations so impoverished as to think chance is by definition the default alternative to conscious design.
*9 I was once asked, in the course of a documentary which I didn’t realize at the time was creationist propaganda, whether I could conceive of any way in which life on Earth could have been intelligently designed. I said that the only way (although I didn’t believe it) would be design by an extraterrestrial intelligence, which would itself ultimately have to be the product of gradual evolution. I’ve never heard the end of it: ‘Richard Dawkins believes in little green men.’
Searching under the lamp-post*1
THE JOKE IS familiar. Man searches diligently under lamp-post at night. Explains to passer-by that he has lost his keys. ‘Did you lose them under the lamp-post?’ ‘No.’ ‘Then why are you looking under the lamp-post?’ ‘Because there’s no light anywhere else.’
The argument has a certain zany logic, and it seems to appeal to Paul Davies, a distinguished British physicist now at Arizona State University. Davies is interested (as am I) in whether our kind of life is unique in the universe. The DNA code, the machine code of life, is all but identical in every living creature that has ever been examined. It is highly unlikely that the same 64-triplet code would coincidentally evolve more than once independently, and this is the main evidence that we are all cousins, sharing a single common ancestor, which probably lived between three and four billion years ago. If life originated more than once on this planet, only one life form survives: our kind of life, typified by our DNA code.
If there is life on other planets, it will very likely have something equivalent to a genetic code, but it is highly unlikely to be the same as ours. If we discover life, say on Mars, the acid test of whether it originated independently will be its genetic code. If it has DNA and the same 64-triplet DNA code, we shall conclude that it is a cross-contamination, perhaps via a meteorite.
We know that meteorites do occasionally travel between Earth and Mars – and, by the way, here is my second example of searching under the lamp-post. A meteorite can land anywhere on Earth, but we are unlikely to find it lying on any surface other than permanent snow: anywhere else it would just look like a stone, and it would soon be covered by vegetation or dust storms or soil movements. This is why scientists hunting for meteorites travel to the Antarctic: not because they are more likely to be there than anywhere else, but because that is where you can clearly see them even when they landed a long time ago. Antarctica is where the lamp-post is. Any stone or small rock lying on top of the snow must have dropped there – and it is quite likely to be a meteorite. Some meteorites found in Antarctica have been shown to come from Mars. This astonishing conclusion follows from a careful matching up of the chemical composition of these rocks with samples taken by robot spacecraft sent to Mars. Some time in the distant past, a large meteorite hit Mars with catastrophic impact. Fragments of Martian rock exploded up into space and some of them eventually ended up here. This shows that matter does sometimes travel between the two planets, and this opens up the possibility of cross-contamination by (presumably bacterial) life. If Earth-life did contaminate Mars (or vice versa), we would recognize it by its DNA code: it would be the same as ours.
Conversely, if we found a life form with a different genetic code – not DNA, or DNA with a different code – we would call it truly alien. Paul Davies suggests that maybe we don’t need to go even as far as Mars to find truly alien life. Space travel is expensive and difficult. Maybe we should be searching right here for alien life that started on Earth, independently of ours, and never left. Maybe we should be systematically examining the genetic code of every micro-organism we can lay our hands on. Every one so far examined has the same genetic code as we do. But we have never systematically searched to see if we can find a different genetic code. Earth is Paul Davies’ lamp-post because it is much cheaper and easier to search among Earthly bacteria than to travel to Mars, let alone to other star systems where the best hope of alien life reposes. I wish Paul good luck in his search under this particular lamp-post, but I am very doubtful of success, partly for the reason Charles Darwin himself gave: any other life form would probably have long ago been eaten by our kind – probably bacteria, we can today add.
I was reminded of all this by a news story in the Guardian:*2 ‘Scientists to scour 1m lunar images for signs of alien life.’ Yet again, the story concerns our old friend Paul Davies, and he is yet again down on his hands and knees, under yet another lamp-post.
If technologically advanced aliens ever visited us, they would be much more likely to have done so in the past than in the present, simply because the past is so much bigger than the present – if we define the present as one lifetime, or even as the span of recorded history. Traces of alien visitations – wrecked spacecraft, rubbish, evidence of mining activity, maybe even an intentionally deposited signal as in 2001: A Space Odyssey – would quickly (by the standards of geological time) be covered over on the actively heaving and vegetation-covered surface of Earth. But the moon is another matter. No plants, no wind, no tectonic movements: Neil Armstrong walked in the lunar dust forty-two years ago, and his footprints probably still look fresh. So, Paul Davies and his colleague Robert Wagner reason, it makes sense to examine every high-resolution photograph ever taken of the moon’s surface, just in case traces are to be seen.*3 The probability is low, but the payoff could be very high, so it is worth doing.
I am very sceptical. I suspect that there is life elsewhere in the universe, but it is probably extremely rare and isolated on far-flung islands of life, like a celestial Polynesia. Visitations to one island by another are hugely more likely to be in the form of radio transmissions than visitations by corporeal beings. This is because radio waves travel at the speed of light, whereas solid bodies travel only at the speed of – well, solid bodies. Moreover, radio waves travel outwards in an ever-expanding sphere, whereas bodies travel in only one direction at a time. This is why SETI (the Search for Extra-Terrestrial Intelligence using radio telescopes) is worthwhile. SETI is not wildly expensive as big science goes, but Paul Davies’ latest lamp-post is a lot cheaper and I again wish him luck.
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*1 This article first appeared on the website of the Richard Dawkins Foundation for Reason and Science on 26 December 2011.
*2 23 December 2011.
*3 The aliens of Arthur Clarke’s story planted their tell-tale ‘tombstone’ signal on the moon so that it could be discovered only by a civilization advanced enough to be worthy of it.
Fifty years on: killing the soul?*1
FIFTY YEARS ON, science will have killed the soul. What a terrible, soulless thing to say! But only if you misunderstand it (easily done, admittedly). There are two meanings, Soul-1 and Soul-2, superficially confusable but deeply different. The following definitions from the Oxford English Dictionary convey what I am calling Soul-1.
The spiritual part of man regarded as surviving after death, and as susceptible of ha
ppiness or misery in a future state.
The disembodied spirit of a deceased person regarded as a separate entity and as invested with some amount of form and personality.
Soul-1, the soul that science is going to destroy, is supernatural, disembodied, survives the death of the brain and is capable of happiness or misery even when the neurones are dust and the hormones dry. Science is going to kill it stone dead. Soul-2, however, will never be threatened by science. On the contrary, science is its twin and handmaiden. These definitions, also from the OED, convey various aspects of Soul-2:
Intellectual or spiritual power. High development of the mental faculties. Also, in somewhat weakened sense, deep feeling, sensitivity.
The seat of the emotions, feelings, or sentiments; the emotional part of man’s nature.
Einstein was a great exponent of Soul-2 in science, and Carl Sagan was a virtuoso. Unweaving the Rainbow is my own modest celebration. Or listen to the great Indian astrophysicist Subrahmanyan Chandrasekhar:
Science in the Soul Page 22