This is the third part of a debate between AC Grayling and Steve Fuller – start by reading Grayling's review of Fuller's book, followed by Fuller's defence.

Steve Fuller complains, as do all authors whose books are panned, that I did not read his book properly (or at all). Alas, I did. And as I did so I naturally thought (again as all authors are apt to do) that I wish he had read the two books I'd previously written on the history of the relation of religious thought to scientific and ethical thinking, in the modern period as regards the former and from classical antiquity as regards the latter. Had he done so he might not - if he had understood them, he could not - have written as he has done in the course of trying to defend the dressed-up version of creationism which calls itself "Intelligent Design theory".

Fuller's endeavour turns in important part on trying to show that science is the child of religion, that its styles of thought are religion's styles, and that the very coherence of the scientific enterprise owes itself to the grand narrative of the religious world-view. Still wishing to spare those forests threatened by the epigones of ID theory and the time-wasting involved in rebutting it, I offer the words of no less an authority than Cardinal Bellarmine, written in 1615 to Paolo Antonio Foscarini, who had tried to show that Copernican heliocentrism is consistent with Vatican doctrine: "As you are aware," so Bellarmine wrote, "the Council of Trent forbids the interpretation of the Scriptures in a way contrary to the common opinion of the holy Fathers. Now if you will read, not merely the Fathers, but modern commentators on Genesis, the Psalms, Ecclesiastes, and Joshua, you will discover that all agree in interpreting them literally as teaching that the Sun is in the heavens and revolves round the Earth with immense speed, and that the Earth is very distant from the heavens, at the centre of the universe, and motionless. Consider then, in your prudence, whether the Church can tolerate that the Scriptures should be interpreted in a manner contrary to that of the holy Fathers and of all modern commentators, both Latin and Greek."

"Consider in your prudence": indeed. This was a decade and a half after Giordano Bruno was burned to death in Rome's Campo dei Fiori for having among his many alleged turpitudes an adherence to the Copernican view; four years before Cesare Vanini died at the stake in Toulouse in 1619 for the same reasons; and just less than another decade and a half before Galileo escaped their fate by denying that the earth moves. (Such are just the salient names.) Copernicus's De Revolutionibus found its way onto the Index of Forbidden Books.

The Vatican, by the way, formally apologised for its prosecution of Galileo on 31 October 1992. The apology came four centuries late; science had long since moved far on. Yet Fuller thinks that science springs from religion. Before you think this is mere absurdity, remember it is because Fuller has to bend and muddle things round so that an ancient creation myth can be fitted into jeans and a t-shirt and made to look hot. This is not ignorance and stupidity: this is trahison d'un clerc.

I addressed Fuller's premises rather than what he seeks to draw from them for obvious enough reasons, but let me just remind readers of why ID theory would be hilarious if it were not a threat - and not just to truth, and science, and the education of the young, but lots more: we could have a creationist president in the US in one heart-attack's time, with all the rest of the garbage that standardly goes with it, such as belief in Armageddon, return to stone age science, the social policy of medieval peasants - ID theory does not lack a penumbra.

But here's the funny bit: your average engineer, tasked with building a human being, would not separate the entrances to the trachea and oesophagus with a movable flap tagged with an instruction not to breathe while you eat, or the organs of generation not just next to but partially carrying the organs of excretion, or redundant bits of anatomy than can become infected and kill their owners, or permanent vulnerability to large numbers of invasive life-threatening organisms, or cells that constantly mutate in potentially life-threatening ways, or the origin of the optic nerve slap in the middle of the retina, or... and so endlessly on. Next time Fuller crosses a bridge or a railway line, let him note the way it allows for expansion and contraction of the materials from which it is made in response to circumambient temperature; and ask him why the soft tissue constituting the brain, apt to swell if bruised, is encased in a rigid box of bone. I take it, on the evidence of his book, he has never had wisdom teeth: had he done so, he might have contemplated the evidence they constitute, in connection with orthognathy, of evolution's blind gropings. Intelligent design? Look in a mirror for the horse-laugh answer to that one. Look at nature - in all its beauty, ugliness, sweetness, brutality, charm, indifference and immense variety - and the idea that it manifests conscious design or purpose, still less intelligent design, is seen for what it is: a little driblet of childish ignorance; a mark of mankind's infancy.

This is what Fuller seeks to defend. That by itself should be enough to stop the conversation. But the combination of misinformation and fallacy with which he persists in doing it merits a few remarks, and they relate to his specific fulminations in his reply to my review.

His book "indeed talks about Thales, Augustine, Galileo and Popper" - but oh so tendentiously. Did Fuller say that Thales regarded the world as intelligible (Fuller attributes this insight to Augustine to show that we owe science to religion) but did not commit the elementary fallacy, standard with the faithful, of thinking that because it is intelligible it must either itself be intelligent, or have been intelligently designed? He quotes Popper, but not in application to religious belief or ID theory, but to evolution - a good challenge by Popper, for it asks that evolutionary theory specify what would refute it and how it can be tested. And so it munificently does. Do any of the things an average engineer would not build into a human body, specified above, count as evidence against intelligent design for ID theorists? Of course not. If it aspires to the condition of science, despite knowing in advance from the Book of Genesis what it wishes to prove, does it regard the clumsy "design" of so much nature as counter-evidence? It does not.

I am, says Fuller, ignorant (sheerly so; this is the glaring deficiency in my case) of "ID's argument structure", which is - argument to the best explanation! Oh pul-eese! I ignored this bit in my review out of a kind of residual collegiality, for even among the toxicities that flow when members of the professoriate fall out, embarrassment on others" behalf is a restraint. But he asks for it. Argument to the best explanation! Look: there is a great deal we do not know about this world of ours, but what is beautiful about science is that its practitioners do not panic and say "cripes! we don't understand this, so we must grab something quick - attribute it to the intelligent designing activity of Fred (or Zeus or the Tooth Fairy or any arbitrary supernatural agency given ad hoc powers suitable to the task) because we can't at present think of a better explanation." They do not make a hasty grab for a lousy "best explanation" because they have serious thoughts about the kind of thing that can count as such. Instead of quick ad hoc fixes, they live with the open-ended nature of scientific enquiry, hypothesising and testing, trying to work things out rationally and conservatively on the basis of what is so far well-attested and secure. What looks like having a chance of being both an "explanation" and the "best" in a specific case turns on there being a well-disciplined idea of "best" for that specific case. But an hypothesis has no hope of becoming the best explanation (until a better comes along) unless it survives testing, is specific, and is consistent and conservative with respect to much else that is secure. This is a far cry from the gestural "best explanation" move that ID theorists attempt, which - and note this carefully - does not restrict itself to individual puzzles only, but applies to Life, the Universe and Everything. It has to, at risk of incoherence; and yet by doing so, it collapses into incoherence.

Fuller, ploughing heedlessly onward, says that the issue here is the question of where the burden of proof lies: with "design or chance". Chance? Here Fuller's ignorance is woefully on show. Who said anything about chance, whether in the aetiology of stars or the biological sphere? Biological evolution is not a matter of chance, but of what happens to genes in the relationship between populations and environments - a causal relationship that conforms predictably to nature's other and general regularities. Stars don't pop into existence by chance; they form out of the operation of gravity on gas. Tea-cups don't unexpectedly give birth to piglets. And even at the quantum level what happens is measurably probable, not random or arbitrary.

As to the burden of proof: the vague and deliberately obscure notion of ID - vague and obscure in order to leave wide the door regarding what sort of agency has the competence to be the ID-er (though as we see above, a not very reliable competence at that) - is implicitly, but only implicitly, defended by Fuller as something provable or disprovable by responsible methods when he says this: the "distribution of the burden of proof reflects little more than a bias in favour of the scientific orthodoxy." Some bias! Here is a little story that explains why one might be "biased" in favour of science as opposed to vaguely invoked putative Universe designers. As follows: Professor Fuller is woken by his alarm clock; switches on the electric light; rises; has a hot shower while the kettle boils; checks the emails on his computer while he drinks his coffee; gets in a motor cab for the airport; flies to New York; takes some aspirin for the headache he acquired through dehydration on the flight; repeats the taxi-email-hot-shower routine after traveling upstairs by elevator in his hotel. At every step he uses, trusts, relies on, profits from, the appliances of science and technology. But he is not biased in favour of science! It would be mere bias to think that all this success and brilliant technology somehow privileges science over - say - prayer! Surely prayer would be as effective in transporting one in a few hours from London to New York? Why not heat the water for one's coffee and shower by dancing in a circle or sacrificing a virgin? It is only bias, says Fuller, that makes science seem more wildly successful and efficacious than - what? Rain-dances and incantations?

"Had Grayling some basic knowledge of the history of Christianity - of the sort a Jesuit education might have provided him" - says Professor Fuller. Well, we've seen what a Jesuit education has done for Fuller. But I'll take on Fuller any day regarding the history and theology of the various versions of Christianity with which humanity has been burdened. My confidence is boosted by his remarks (not his words; perhaps he does not know the formulation) about the Protestant view that each is his own priest before God, for that is proof positive that he has no conception of how that has in fact played out in (for example) the hands of the Calvinists, or since then in the evangelical and Pentecostal movements. The same applies to the history of science: Fuller cannot ever have seen that passage from Bellarmine above if he thinks modern science owes its birth to religion. If he seriously thinks this latter, he has hugely wasted his time as a putative student of the history and philosophy of science. But it is of course logic that is either lacking from Fuller's education, or his version of (to borrow his phrase) its head-banging Jesuit variety which he lauds as enabling "reconciliation of irreconcilables". For he says, again revealing the sheer lack of understanding that underwrites the fallacy he commits, "our current level of scientific achievement would never have been reached, and more importantly that we would not be striving to achieve more, had chance-based explanations dominated over the design-based ones in our thinking about reality."

Let us make the fallacy here completely clear. His thinking proceeds thus: "Natural things and processes have structure, and behave in generally regular ways. You can call this structure and these regularities the 'design' of these things and processes. But they can only have a design if they are designed by a designer. The only alternative is that they came to be thus 'by chance'." The sloppiness is obvious, but here it is for Fuller's sake: First, there is the slip from structure to "design" - harmless enough, if "design" is understood as being the analogy it is. Then there is the woeful slide from "having a design" to "having a designer". Compare "natural things have a structure, so they have an intelligent structure... natural things have a shape, so they have an intelligent shaper." Then there is the absurd claim that the only alternative to intelligent design is chance presumably in the sense of arbitrariness, randomness, accident. That's dealt with above.

Fuller says that seeing the philosophers of classical antiquity as doing science or proto-science is like "seeing heads of animals in the clouds." Coming from a defender of ID that is a pretty rich image! and it made me laugh, which is always nice. But let me get this straight: Fuller says Thales and Anaximander and Anaximenes and Democritus and Leucippus etc were not interested in the arche of the universe - do not one jot merit their collective label of "the physicists" - did not variously and in preliminary fashion wonder whether matter consists of fundamental physical particles (atoms - but of course not atoms as intelligently designed by a god!) and the evolution of animals from sea creatures... or work out the extent of the earth by geometrical means, or construct theories of the planets...? Fuller knows something about them that the rest of us don't, evidently! He even says that the antique philosophers "would find the enterprise [of modern science] itself abhorrent - with its endless questing for an elusive yet uniquely comprehensive understanding of reality." Well, well. And why? Because enquiry was for the Greeks a leisure activity alongside physical exercise, says Fuller, so it cannot have been science. This, you see, is the kind of claim our excited friend allows himself to make - triumphant assertions of the form "black is white". It would take too long to unpick all this, so I shall extend an invitation to Fuller to join our undergraduates at Birkbeck for a refresher on the Greeks, and he can try this argument again later.

Fuller says I am confused about atheism's contribution to science (I let my original remarks stand on this one) and that anyway, he does not think there is any such thing as atheism - he says, "I have yet to be convinced of the existence of atheism" - which makes it puzzling as to why he can nevertheless find it worth claiming that it has made no contribution to science. (Neither have unicorns, for the same reason if Fuller is right). Fuller says quite rightly that I am opposed to dogmatism and clericalism, and it is true that there might be a (sometimes perhaps slightly confused and not very happily placed) theist who, by imagining that the baby was still in the bath after the water had gone, thought likewise. But the point is that theism - to which an atheist is by definition opposed - just is some sort of dogma often administered by some sort of clerisy (e.g. there is no Christ or Virgin Mary, just the church that mumbles those names). So it requires a kind of contortionism, not impossible but painful, to think that one is opposed to some of the -isms but not the intimately associated ones, especially the ones that make the other -isms appear to have a modicum of meaning.

But let us finally dispense with the huge bolus of nonsense at the centre of Fuller's efforts to see religion as the progenitor of science, which he does by claiming that "philosophers and scientists continue to believe in a transcendent reality" of a religiously-originated sort, which will "reward" continued efforts to understand it, and which has given us our ideas about the intelligibility of nature and our faith in being corrigible though fallible. Like some others, Fuller wants to see religion (actually, Christianity: the other major religions do not even begin to allow the narrative reading to start) as giving us our idea of the odyssey, the quest, for truth and understanding ("salvation" secularised), a plumbing of mysteries and a searching out of hidden meanings, our errors and stumblings on the way justified by the faith that we can get there in the end. Thus one sees the trick: the infection of the argument by religious terminology to sacralise what is essentially so different from the static metaphysics, the unchanging and marmoreal already-revealed Truth of the faith, which requires not investigation and questioning - for that you die at the stake - but submission, acceptance, obedience, worship. Religion, in short, is so absolutely different from the enterprise of science that efforts like Fuller's to patch up religion's bad name by annexing science to it - science, which had to fight tooth and nail to get out from under religion's not infrequently punitive hegemony - just will not do.

And all this leaves out of account the opaque connection between science even as thus misunderstood and the defensibility of the idea that nature manifests "intelligent design". But - life is too short.

And finally as to humanism. Humanism in today's acceptation of the term is the view that our ethics and politics should be premised on our best understanding of human nature and the human condition, as revealed to us by empirical enquiry and by the arts, literature, reflection, and the grown-up conversation of mankind. It refuses to accept that instructions for how to live, act and believe come from the far past or outside space and time, and it refuses to believe that the whole point of life is to get membership of a posthumous choir. Science has a great part to play in aspects of the humanist endeavour, and in its turn has to be tempered and shaped by it. The example set by science, as by an infinite distance our best epistemology, is crucial to humanism; and that is why the pursuit of the good has to include taking the time - and you have taken up a lot of my time here, Professor Fuller, on your absurd views - to rebut the kind of nonsense that is ID and creationism and the associated ancient fairy-tales they emerge from.

This is the third part of a debate between AC Grayling and Steve Fuller – start by reading Grayling's review of Fuller's book, followed by Fuller's defence.

Just added: Fuller and Grayling continue the debate in the forums