Secret Codes, Holy Grails & our Fascination with the Improbable

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This talk, though intended to be light-hearted in its approach, is motivated by a very real concern. In recent years the world has seen a worrying slide towards irrationality and gullibility. Perhaps as a result of the decline of formal religion, a host of strange and unlikely beliefs have arisen and grown in popularity. From homeopathy to alien abductions, from spoon bending to ‘end times’ predictions, more and more people seem more and more willing to suspend their critical faculties and accept improbable, unlikely and fantastic claims. This talk sets out to consider why, using the phenomenon of the bestselling Da Vinci Code as a case study.

The first question to ask is; do we have a reliable, tested and rigorous method of arriving at accurate truth-statements about reality? And secondly, if we do, why are so many people apparently so willing to dispense with this method, and rush to believe improbable claims?

This then determines the format of the talk, which begins by looking at the best method yet discovered for accurately describing reality; critical rational thought, and its most rigorous expression; the scientific method. The talk then moves on to consider why, if we have such a tested and reliable tool, are people so willing to dispense with it? We argue that this tendency was due to two sets of factors, which could broadly be grouped under the headings of evolutionary hangovers, and secondly flawed reasoning. Finally we ask the question; does it matter? Are such beliefs harmless crack-pottery, or do they have more serious implications?

Critical, Rational Thought.

Critical, rational thinking has been repeatedly shown to be the most reliable method of arriving at accurate statements about reality. The fact that you are reading this is evidence of that, since the technology that you are relying to do so is a product of this approach. All around us, every day, we are surrounded by the products of the rationalist approach, and it would be hard to imagine life without them. Perhaps the highest expression of this approach is the scientific method, but before looking at this in more detail, a word on definitions.

Proof: This is a word that is bandied about quite loosely. People will say ‘ah, but there’s no proof of that’, or they’ll point to the fact that scientists acknowledge that such and such a claim has not been proven. Nothing in the real world is ever proven. Proof exists only in the self-contained realm of mathematics.

In the real world we can never be absolutely certain about the truth of any claim or proposition, if only because we could, in theory, be ‘brains in a jar’, sitting in a lab somewhere being fed artificial stimuli.

While I am not for a second suggesting that this is the case, the fact that it is theoretically possible means that we can never be absolutely certain of anything beyond our awareness of our own thought processes; I think, therefore I am, as Descartes put it. This is the limit of what anyone can know with absolute certainty. Beyond that, we are left with propositions that may be assigned a probability value. This value runs from 0, (the proposition is absolutely definitely untrue), to 1, (the proposition is absolutely definitely true). Nothing in the real world can ever have a probability value of 0, and nothing can have a probability value of 1.

For example, how do you prove that unicorns and leprechauns don’t exist? You can’t. You can say that absolutely no evidence has ever been adduced to support their existence, and that their existence would contravene what we know about the way the world is, but unless you could simultaneously visit every part of the universe and observe the absence of unicorns and leprechauns, you cannot say with absolute certainty that they don’t exist. Only logically impossible concepts, (such as hot snow or a pillow made of memories), can have a probability of 0.

Some propositions may approach a probability of 0, such as leprechauns, unicorns, bankers declining bonuses etc, or may approach a probability of 1, such as the existence of the chair you’re sitting in, the theory of gravity or the germ theory of disease, but in the real world nothing is absolutely proven or disproven.

Theory: There is much confusion about this term, largely arising out of the fact that its usage is different in scientific parlance and everyday language. People say things like, ‘well, that’s only a theory’, failing to realise that in science ‘theory’ represents the very highest status that an explanation can attain, and one that it can attain only after a rigorous and exhaustive process of examination and review. Many people use the word theory as a synonym for ‘guess’ or ‘hunch’, (I have a theory about who used the last of the milk), but this is not the way the word is used in academic discourse.

Fact: How many times have you heard, ‘it’s only a theory, it’s not a fact’? As if somehow theories, if they’re really good and go to bed early, will grow up to be facts. A fact never becomes a theory, a theory never becomes a fact. In science ‘facts’ occupy the lowest rung on the ladder, they are the least important concepts. A fact is simply the verifiable occurrence of a particular event. A theory is what we use to trry to explain a connected series of facts. The best theory available in any given situation is the explanation that can best account for the known facts, and that fails to account for none of them. Theories explain facts, they never become them. To reinforce this notion let us consider the scientific method, perhaps the most rigorous example of critical rational thinking at work. We do this for two reasons; firstly to give the audience an appreciation of just how hard an explanation has to work in order to be called a theory, and secondly to contrast this careful and rigorous approach with what could be called the ‘conspiracy theory’ approach.

All science begins with three wonderful and magical words, the most beautiful words in the English language; ‘we don’t know’. An honest acknowledgement that we don’t understand a process, or can’t explain a phenomenon, is the beginning of the process of discovery. It invites enquiry and investigation. In contrast declaring that we know the answer, and cannot be wrong, brings enquiry and investigation to a halt.

So having decided on the problem to examine, the researcher must then formulate a hypothesis; a suggestion or hunch about what the answer might be. But while a particular hypothesis may appear correct, and may fit the facts, if not examined further it has no value. A hypothesis must be tested to be of any use. So in reality, conspiracy 'theories' should not be called theories at all. They are untested hypotheses.
To test the hypothesis the researcher must formulate a falsifiable prediction. In other words, ‘if this explanation was correct I would expect X to happen’, and then go out and devise an experiment that tests whether or not X actually does happen. Let us take a hypothetical example, to illustrate the approach.

Let us take an imaginary researcher, Professor Jane, who is intrigued by the question of how pigeons manage their amazing feats of navigation. Casting around in her mind for an explanation she hits upon an educated hunch. Jane remembers reading a paper some time ago which revealed that pigeons have a bone in their skulls that carries a weak magnetic charge. She wonders if the pigeons are using this bone almost like a compass.

Jane now has her hypothesis. Her hunch is reasonable, it fits the facts, and it explains the problem. But at this stage her idea is worthless. This is because it has not been tested. So many conspiracy theories stop at this stage, they suggest a plausible explanation, one that could be true, but never go on to test whether it is or not.

So Jane must now formulate a falsifiable prediction, a prediction that is capable of being tested and shown to be incorrect. This is an important point, scientists don’t set out to ‘prove’ a hypothesis correct, they set out to test if it is incorrect.

So Jane reasons that if she can construct a small device that interrupts the magnetic field generated by the pigeons they should lose all sense of direction and, if female, stop other pigeons and ask for directions, and if male, say nothing but keep wandering around in the hope of eventually finding the right route. So Jane builds a small helmet capable of damping the magnetic field, fits it to her test subject and, lo and behold, it loses all sense of direction. Does Jane now have a theory? Not by a country mile.

How do we know there wasn’t something wrong with that particular pigeon, something about the weather conditions that day, or some other factor?

Jane must repeat the experiment, with a suitably large sample of pigeons, of different breeds, ages, in different weather conditions etc, and only if she gets repeated and regular results can she be said to be on to something. But even this is not enough. How does she know that the results she is getting are not due to some other factor that is common to all the pigeons, but which she hasn’t accounted for? So she needs a control group, a second group of pigeons that are as far as possible identical to the test group in terms of breed, age range etc, and who have made for them little helmets, identical to the test helmets but for the magnetic damping effect. Only if Jane gets the expected effect in the test subjects, and fails to get it in the control group, can she be reasonably confident that the effect is due to the phenomenon being tested.

But Jane is not out of the woods yet. She must now face what for most researchers is the most daunting hurdle to clear; she must get her work published in a recognised peer reviewed journal. The peer review process involves submitting her work to the examination and scrutiny of a panel of other experts in the same field, who will tear it apart looking for errors. Was the sample group properly selected? Was the testing conducted to the required standard? Did Jane account for all alternative explanations? Did the results show what she said they showed, or could they be due to some other factor? Only if her work clears this hurdle can Jane be said to have developed a recognised theory.

The peer review process represents a vital check. It ensures that research must be independently verified before being published, and that is has met the required standard. No claim that has not been subject to this scrutiny can be of any merit.

This is the case with US creationists for example, who are actively trying to get the biblical account of creation taught in American schools as a scientific theory of equal merit to the theory of evolution. They protest that all they are seeking is equal treatment, that the two theories be presented to schoolchildren as equally plausible alternatives. But in fact they are looking for preferential treatment, since their hypothesis has not been subject to the rigorous and thorough process of review and examination that the theory of evolution has been.

To date there hasn't been a single piece of research published in a recognised peer-reviewed journal that supports the creationist hypothesis. There have been many thousands of such studies published that support the theory of evolution, yet creationists want the two approaches treated as if they are of equal value.

Even after Jane has had her theory published she is still not out of the woods, and in fact she never will be. Her work is now open the scientific world for critical review. Other researchers may repeat her experiments. If they do, they must get the same results. If they don’t, something is wrong. Her theory must be consistent with what we already know about how the world works, and must remain consistent as new discoveries are made.

No theory is ever finally proven. There are no sacred cows in science, no individuals or theories that are beyond question. Science follows where the evidence leads, regardless of whether this does or does not fit in with what individual scientists would like to be true. No matter how important a theory is, how respected its formulator, or how long it has been around, if a better theory comes along it will be dropped.

So we have at our disposal a reliable, tested, rigorous method of examining the world around us and arriving at accurate statements about reality. Why is it then that so many of us seem to willing to abandon this method, and accept highly improbable claims? It is because of two sets of factors; a hangover from our evolutionary past, and the application, sometimes deliberate, of flawed reasoning.

2. Evolutionary Hangovers.

Our brains are just as much a product of the evolutionary process as our bodies. As with our body, our cognitive process can sometimes throw up unhelpful or incongruous results, a sort of mental appendix or coccyx.

It is often said that humans are pattern seeking animals. We seek out relationships between events, looking for connections and patterns. This conferred a huge advantage on us in our evolutionary past. Noticing that a particular pattern of clouds precedes a particular type of weather, or that a particular colour of soil produces particular results when planted, would have huge survival implications for our ancestors. Humans today are the product of hundreds of thousands of years of a process that drives us to seek patterns. We abhor randomness.

Pattern seeking has produced hugely beneficial results. The Egyptian civilisation, for example, was largely built on their ability to predict the annual flooding of the Nile, which was discovered because people saw a pattern, noticed that the annual rising of the Dog Star (Sirius) was followed by the beginning of the Nile flood. Being able to accurately predict this event allowed them to prepare for it, and take full advantage of it. The problem is that so strong is this urge that we will see patterns even where none exist, and are very suggestible in this regard.

A classic example is the famous canals on Mars. When astronomers first turned their telescopes to the surface of Mars they were astonished to see the it was covered with long straight lines. What could they be but canals? The Martian canals aroused huge debate and speculation, but unfortunately didn’t exist.

What had happened was that early telescopes were not good at resolving surface detail, and instead showed random scatterings of hazy blotches and marks. The human mind hates randomness, and our innate urge to sort random phenomena into patterns took over and arranged the blotches and blobs so that scientists ‘saw’ straight lines.

But this instinct can also be exploited for more sinister purposes. One of the mainstays of Hitler’s rabid propaganda was the claim that communism was the product of an international Jewish conspiracy, that it had been concocted by Jews in order to undermine western society. His evidence? Well, Nazis pointed out, Marx was Jewish, so was Lenin, so was Trotsky. Gullible people gasped and said, ‘my god, he’s right’! What the Nazis were doing was imposing a pattern on unrelated events, suggesting that these were not isolated facts, but fitted into an overall scheme. Our instinctive need to find patterns did the rest. Another evolutionary hangover that influences our susceptibility to conspiracy theories is our instinct to see agency in ambiguous situations.

‘Agency’ in this context refers to the actions of a mind or a conscious actor. An ambiguous event, for example the rustling of grass, could be the result of naturalistic process, e.g. the wind blowing, or it could be the result of agency, e.g. an animal moving in the undergrowth. It doesn’t take too much imagination to see that a propensity to plump for the second explanation would confer an evolutionary advantage, since the rustling might be due to a sabre toothed tiger.Our less easily startled ancestor therefore was at greater risk of being eaten, since his more nervous companion would have taken to his heels.

We are the product of a couple of hundred thousand years of natural selection that urges us to see a conscious mind behind every situation, on the very sound basis that in the past that could have saved our lives. But as with our pattern seeking behaviour, we have a tendency to see agency even where none is present. This was probably the basis for most ancient religions, which saw naturalistic processes, such as the rising of the sun or the flowing of a river, as being directed by a conscious mind.Hence the Greek belief that the sun was pulled across the sky each day by the god Helios, or pagan beliefs that trees and rivers were inhabited by spirits.

This tendency then leaves us very susceptible to suggestions that conscious minds lie behind random events. A lot of the 9/11 conspiracies, for example, make use of this effect. They cite the catalogue of errors and slip-ups that made the attacks possible; the intelligence lapse, the poor reaction of the security forces, etc, and suggest that a conscious mind directed these events. Our atavistic desire to see agency at work then kicks in, and we find these claims much more instinctively satisfying than the far more probable explanation; human fallibility and random cock-up

3. Flawed Reasoning.

So human minds are programmed in a way that makes them susceptible to improbable claims in certain circumstances. This tendency is then compounded by errors in reasoning.One is a failure to distinguish between a particular explanation being consistent with the facts, and the explanation being supported by the facts, and these are two very different propositions.

An explanation or hypothesis is consistent with the facts if there is nothing in the facts that would contradict or refute the particular explanation. An explanation is supported by the facts if the facts are such as to suggest that this explanation is likely to be correct, or more likely to be correct than any competing explanation. Time and again conspiracy theorists devise explanations that ‘fit’ the facts, and then because there is nothing in the evidence to contradict the explanation, claim therefore that their theory is supported. But a theory can be completely outlandish and yet be consistent with the facts.

Take a deliberately stark example. My car is parked outside. The doors are locked and my keys are in my pocket. These facts are consistent with the theory that I drove here, parked up, locked the car and came in.

But they are equally consistent with the theory that I’m on first name terms with the captain of the Starship Enterprise, that he flew over my house and used his matter transporter to beam me up, then flew over and beamed the car back down again. The facts as presented above are entirely consistent with both explanations.

So have I demonstrated the existence of the Enterprise? Of course not. But why not? Why is the first explanation more acceptable? It is useful to ask this question in this case, because although this is a deliberately obvious example, the same method is frequently used in more subtle guises to dupe the unwary into accepting outlandish theories.

There is a very useful intellectual tool that can assist us in this regard; Occam’s Razor. This was devised by William of Occam, (or Ockham), a fourteenth century Franciscan monk and philosopher. Essentially he argued that in a situation where we are confronted with a number of competing explanations, we should ask how many assumptions need to be made in order for each explanation to be true, (and how outlandish are those assumptions).

All things being equal, the rational option is to go with the explanation that requires the fewest assumptions. This principle has been enunciated in various guises. Occam himself stated it as "entities must not be multiplied beyond necessity", and it is frequently popularised as “the simpler an explanation is the more likely it is to be true”, which doesn’t quite capture what Occam was arguing.

Applying this to the above example, we would ask how many assumptions need to be made in order for each explanation to be true. Well, for the first explanation to be true we need only assume that I know how to drive, (anyone who has gotten a lift from me may by now be convinced of the existence of the Starship Enterprise).

But in order for the second explanation to be true we must make a whole raft of assumptions, all of them highly improbable. We must assume the existence of extraterrestrial civilisations, advanced technology, interstellar star travel, matter transporters etc. etc. etc. This is a deliberately obvious example, but it is a tool that can be applied when confronted with any improbable claim.

I like to conceive of this in terms of a ladder of improbability, with simplest, most probable explanation at the bottom, and the most outlandish at the top. The rational approach is to start at the bottom, but so many theories start at the very top, with the most improbable and fantastic explanation, even where simpler and more probable explanations exist.

Of course, one may come across a piece of evidence that cannot be accounted for with the very simplest explanation. Going back to the above example, you may go out to my car shortly after I arrive and put your hand on the engine and find it stone cold. Now we have a problem, because here’s a fact that the very simplest explanation cannot account for. So have I now proved the existence of Star Trek? No, because there are still plenty of rungs left in the ladder. The next likeliest explanation could be that I was towed here. It’s not as probable as the very simplest explanation, but its infinitely more probable that the Starship Enterprise theory.

A useful maxim here was coined by the late, great Carl Sagan; “extraordinary claims require extraordinary evidence”. You may feel that a car with a cold engine is sufficient evidence to support the existence of interstellar starships, but I doubt it. The more fantastic the claim is, the more it deviates from the norm or challenges the accepted view of how the world works, the higher the standard of evidence we should demand.

This is not to say that a fantastic claim is necessarily wrong, merely that we should require evidence in exact proportion to the improbability of the claim being made. Yet it is amazing how many times vast edifices of improbability are erected on the very flimsiest of evidence.

But by far the greatest culprit when it comes to conspiracy theories is that of confirmation bias; the propensity to decide that an explanation is true, then carefully select only the evidence and arguments that support that belief. If you think back to Professor Jane, one of the features of the scientific process is the importance attached to considering all possible explanations, of not assuming that a particular explanation is true, but of checking and rechecking to ensure that other possible explanations have been considered and accounted for.

This why if you read a book on a conspiracy theory, for example many of the 9/11 theories, you may very well come away convinced, because the author has started with the assumption that their theory is correct, then selected only those facts that support this conclusion. Any contradictory evidence is ignored or dismissed. If any reputable scientist tried this approach their work would be rejected out of hand.

There have been several interesting experiments done that illustrated this tendency. In one, test subjects were shown a short number sequence; 2,4,6… told that that the sequence conformed to a rule, and they had to discover what the rule was. This they could do by putting other number sequences to the researcher, who would tell them whether or not they too conformed to the rule. When they thought they knew what the rule was they were to tell the researcher.

In almost all cases the subjects looked at the sequence and concluded that it was obviously a series of increasing even numbers. To confirm this they then submitted other sequences to the researcher, such as 8,10,12… or 16,18,20… In each case the researcher confirmed that these too conformed to the rule, whereupon the subject would triumphantly announce that the rule was ‘increasing even numbers’, and were all disappointed to be told they were wrong.

In fact the rule was ‘any series of increasing numbers’, but what almost every test subject had done was take one look at the sequence, decide what the rule was, then only submit other sequences that also conformed to that rule. Few if any submitted a sequence that contradicted their assumption. Everyone sought to confirm the conclusion they had already reached, hardly anyone sought to challenge it. So people are quick to reach conclusions on partial evidence, and loath to then challenge their assumptions. A second problem is that having arrived at a conclusion, people are very unwilling to abandon it, even if shown that the evidence upon which the assumption was based is faulty. Another experiment nicely illustrated this tendency. A group of people were asked a simple question; which type of person did they think made the best fire-fighter; a cautious person who always followed procedure, or a daring risk-taker who was prepared to take chances?

Like most people, the test group had no particular insight into fire-fighting, and so there was no clear pattern in their answers; about half said they didn’t know, the other split roughly evenly between the two options.

The group was then given a paper purportedly written by a long-serving fire-fighter, who set out their opinion that the risk-taker made the better fire-fighter. They were asked again who they thought would be best, and now some 70% opted for the risk-taker. Again all nice and rational; they were given new evidence, and adjusted their answers accordingly.

But then they were told that the paper they had just read was a fake, it was made up by the researchers. They were asked a third time who they thought was best. Rationally, they should have now returned to their original neutral position, as they had been shown that the evidence which they had used to reach their last conclusion was faulty. But instead some 60% stuck with the opinion that the risk taker was better.

This is why, if you are ever dealing with someone who has already decided that a conspiracy exists, it can be enormously difficult to get them to question that belief, even if you present them with persuasive arguments and evidence. Some people will perform mental gymnastics in order to carry on believing what they believe.

Science attaches great importance to eliminating confirmation bias. For example, when a piece of the Turin Shroud was finally allowed to be carbon-dated some years ago, it wasn’t simply submitted to a lab and tested. Instead the sample was divided into three parts, and each part was sent along with two other similar samples to three different labs. None knew which was the sample from the shroud and which were the control samples. They were just given three samples marked A, B, and C, (or whatever), and asked to date them. All nine test results were then collected, and only then was it revealed which was which. (All three labs dated their portion of the shroud to the 13/14th century, by the way).

A final point before launching into the Da Vinci Code. You will rarely if ever get complete unanimity on a particular theory, or get a situation where all the evidence supports a particular conclusion, and none supports any rival explanations. You can always find, if you look hard enough, a scientist who disagrees with the consensus in a particular area, or a piece of research that doesn’t quite fit the accepted view.

What matters is where the preponderance of evidence lies. Does the bulk of the evidence or scientific opinion point to a particular conclusion? If the overwhelming weight of the evidence points in a particular direction, but you chose to reject it in favour of a theory for which there is far less evidence, you need to ask yourself why. Are you choosing to go with that theory for rational reasons, or are there other factors at play?

Take, for example, the current debate over climate change. The overwhelming weight of evidence, research and professional opinion supports the argument that our climate is undergoing unprecedented change, and that human activities are a major cause of this change.

Yet many stubbornly refuse to accept this conclusion, and will point to this particular piece of research, or the opinion of that particular scientist, to support their conclusion. They will highlight the very few studies that do not support the thesis, but happily ignore the overwhelming body of research that does. You can always find such studies. If you look hard enough you can probably find a scientist that rejects the germ theory of disease or even the theory of gravity. But if the overwhelming preponderance evidence points to a particular conclusion, and a person refuses to accept that conclusion, then they are probably doing so for non-rational reasons.

These reasons might include a fear of the consequences of accepting the theory, the fact that it might conflict with other beliefs that they hold, or perhaps there are financial or other benefits to rejecting the theory. But in every such case their reasoning is non-rational, and may even be irrational.

4. Case Study - The Da Vinci Code.

Dan Brown’s book the Da Vinci Code was published in 2003 and became an instant best seller. It covered similar ground to an earlier work called The Holy Blood and the Holy Grail. While the former was a novel and the latter a non-fiction work, a similar claim formed the main theme of both works, revolving around the figure of Mary Magdalene.

According to the book, she was not the peripheral figure she is represented as in Christian tradition. She was of central importance, and in fact was the wife of Jesus.

More than that, she was pregnant with their child at the time of Jesus’ crucifixion, following which she gave birth to a daughter and fled with her in a boat, ending up in the south of France. Their daughter grew up to found the Merovingian dynasty, one of the first great dynasties of Europe and the first royal house of France.

These events lie at the heart of the Grail legend, which referred not to a cup, as commonly supposed, but to the sacred bloodline; the bloodline of Christ himself. In French the term Holy Grail was translated as San Greal, but in fact in early writings it is spelt Sang Real, which literally means Royal Blood, i.e. the blood (descendants) of Jesus.

In 1099 a secret organisation known as the Order of the Priory of Sion was formed to protect this holy bloodline. It has been manipulating history behind the scenes ever since, to ensure that the great secret remains secret. Its members have included some of the most influential figures in European history, including Isaac Newton and Leonardo da Vinci. Secret documents were discovered in the Bibliotheque Nationale in Paris that attested to these facts.

In 1119 the Knights Templar were formed in the Holy Land, essentially as the armed wing of the Priory. They were stationed in the Temple of Solomon in Jerusalem, and began digging under the Temple, where they unearthed documents which proved the Jesus and Mary Magdalene claims. These documents enabled the order to grow in power and influence, and explains their spectacular rise from an order founded by two impoverished knights, to one of the richest and most powerful organisations in Christendom.

But there are secret clues to the truth left around for those who know how to find them. In his painting of the Last Supper Da Vinci left a number of such clues which, if read correctly, reveals the great secret.

This then is the conspiracy theory at the heart of the book. How do the claims stand up to scrutiny?

Let us begin with the claim that Jesus was married. The evidence for this is fairly thin, and derives mainly from the fact that nowhere in the bible does it say that Jesus wasn’t married. This is not as silly as it sounds at first. In Jewish society at the time it would have been extremely unusual for a male in his thirties not to married, and the argument is that if Jesus had been unmarried it would surely have been remarked upon.

This type of argument is known as the argument ex silencio, the argument from silence, and scholars always approach it with great caution. Essentially the argument is ‘if X had occurred it would have been remarked upon. X was not remarked upon, therefore X did not occur’. Expressed in this way, it is obvious that an untested and untestable assumption lies at the heart of the argument, hence it is treated with great caution.

We have many instances of major events going completely unremarked by contemporary commentators. One of my favourite examples is a series of letters written between a Protestant minister in the west of Ireland and a clerical friend of his in England. Each wrote to the other each month with the news from their parish. The letters were exchanged each month during the years of the Great Famine, yet not one of the letters contains a single reference to it. Are we to conclude from this that the famine never happened? A conspiracy theorist could certainly use this anomaly to argue so.

Another point is that while it would be extremely unusual for an ordinary male to be unmarried at 30, Jesus was not an ordinary male. He had styled himself, and was seen by his followers, as a wandering holy man and preacher, and it was quite accepted for holy men to be unmarried, and usually celibate. So it is fair to say that the preponderance of expert opinion among biblical scholars is that while this is an interesting question, on balance the evidence suggests Jesus was not married.

But even if we accept that he was married, how do we get from that to Mary Magdalene being pregnant, the child being female, the family fleeing Palestine, the family ending up in France, the daughter founding a royal dynasty? Think back to my car with a cold engine. Does this support the case for interstellar travel and spaceships? This is a classic case of a huge edifice of improbable claims being erected one tiny piece of contested and shaky evidence.

The only evidence that can be adduced in this case is a local legend in the French coastal town of San Marie de la Mere. Here they hold an annual festival to commemorate the arrival of the ‘two Mary’s’, who according to local legend were refugees from the Holy Land who arrived in the town by boat shortly after the crucifixion, accompanied by a female child named Sarah, which means ‘princess’ in Hebrew.

This version of the legend got its first airing in a book called The Lady with the Alabaster Jar by Margaret Starwood, in which she argued that one of the women was Mary Magdalene, and that the child Sarah was her daughter. Again, this is a classic case of pattern-seeking. Several facts are adduced, (if they can be called facts), and a pattern is weaved over them, then presented to us as the only viable explanation. But what we are presented with is one possible interpretation of some very sketchy evidence, with a huge amount of speculation built on. If you wanted to, you could interpret these ‘facts’ to support the theory, but is this explanation the most likely one available? How about a few strokes form Occam’s Razor?

St. Sarah; 'Sarah the Black'. Patron saint of Romany Gypsies.To begin with, if we go back to the legend the locals in San Marie de La Mere are quite clear about who is in the boat. The two Mary’s are Mary Salome and Mary Jacobe, two minor figures in Christian tradition. And the mysterious child that accompanies them is not actually mysterious at all. In fact she is St. Sarah, also known as Sarah the Black, (because she was Egyptian), who went on to become the patron saint of the Romany gypsies. The annual celebration at San Marie de la Mere is in fact one of the most important cultural events in the Romany calendar.

So apply Occam’s razor to the two alternatives. How many assumptions have to be made in order for each to be correct? How extravagant are those assumptions? How great a violation of probability is required, and is the evidence adduced sufficiently extraordinary to justify the claims? Where on the ladder of probability are we being invited to stand? I leave it to the reader to decide.

What about the Knights Templar? They are a well known and well documented organisation, with a history that is fascinating in its own right. They were indeed stationed in the Temple of Solomon, but what about excavations?

Well, there is absolutely no evidence of any excavations ever having been conducted under the Temple until recent times. Now, a complete lack of any evidence has never been a bar to a good conspiracy theory, but another problem is that archaeologists have only begun to reach biblical strata in their diggings in the last century or so. Jerusalem has been built over again and again, and it has been estimated that had the Templars tried to excavate down to the biblical level it would have taken them about 140 years to do so.

So what about their great wealth? The source of Templar wealth is more prosaic than in the conspiracy theory version, but just as fascinating. The Templars became wealthy because they in effect invented the international money order.

In 12th century Europe moving large quantities of money from A to B was an extremely expensive and risky undertaking. Firstly, almost all money was in the form of gold, gold coins or precious stones. It could be moved either by land, requiring a large escort and running the risk of attack by bandits, or by sea, risking pirates and storms. In either event that process was slow, risky and very expensive.

What the Templars did was establish a series of Templar Treasuries, (in effect mini-castles), across the Holy Land and across Europe. If a lord in Jerusalem wanted to send a large quantity of gold to Paris, for example, all he did was deposit the gold in the Treasury in Jerusalem, where he would be issued with a receipt. This he would then take or send to the Treasury in Paris, who would release the required amount in gold, and of course pocket a hefty commission. So huge was the demand for the service that the Order could barely keep up.

So again we have two alternative explanations of the facts, and a rational person would have to ask themselves which was the more plausible, which was more probable, and which required the fewest assumptions.

We turn now to the claim that has perhaps aroused the most interest; the clues supposedly hidden in the painting of the Last Supper. A secret code is a prerequisite of any good conspiracy theory, but I have never understood the reasoning behind them. Why go to considerable trouble to cover something up, then go to more trouble to leave clues to the cover up lying about the place? I have never seen a plausible reason given for this, and cannot understand why it would be in the interest of any conspirator to do so.

Be that as it may, we are presented with the claim that Da Vinci’s ‘The Last Supper’ contains such clues. What are they?

Well the main clues centre around the figure on Jesus’ right, which according to tradition is the Apostle John, but according to Brown is in fact a woman; Mary Magdalene. This figure, Brown argues, is very obviously female. ‘She’ sits in the place of honour on Jesus’ right, and even wears complementary clothes.

Another major clue refers to something that is missing; the grail. This is a painting of the Last Supper, yet where is the cup that was used at the last supper, the Holy Grail? Why is one of the central features of the event missing? It is missing because Da Vinci was alluding to the fact that the Holy Grail was not in fact a cup. As mentioned above, the Holy Grail actually referred to the sacred lineage of Jesus. The Holy Grail is there, it is in fact Mary Magdalene. She is the Holy Grail of legend, the bearer of the sacred bloodline!

Let us start with the ‘feminine’ figure of John. What we are doing here is imposing 20th century conceptions on 14th century European culture. ‘Male’ and ‘female’ refer to sex and are biological terms. ‘Masculine’ and ‘feminine’ refer to gender, and are social and cultural terms. Dominant understandings of masculine and feminine change over time and across cultures. The point is that what we would now consider to be a ‘feminine’ figure would not have been seen as such in 15th century culture.

an English knight St. Sebastian

Take these two figures. The one on the left is of St. Sebastian, on the right an English knight of the 100 years war. While both figures strike us as feminine, they would not have seemed so at the time. The figure below is another one that would appear to be ‘obviously’ female, but is in fact a painting of St. John the Baptist by Da Vinci.

St. John, ‘the apostle'

It must also be remembered that St. John, ‘the apostle whom Jesus loved’, was traditionally represented as a beautiful and youthful figure. On the right is another painting of the Last Supper by a contemporary of Da Vinci, with St. John being the figure on Jesus’ left.

What about the position of the John figure, and the similarity in clothing? Well, we don’t know, as Da Vinci never left any clear explanation of what his intention was. But is the Dan Brown explanation the most probable? How many assumptions need to be made in order for that explanation to be correct?

On the other hand, we know Da Vinci was commissioned to paint the Last Supper in accordance with the account contained in St. John’s gospel. Might not the figure of John be portrayed as he was as an allusion to the fact that it was his version that was being depicted?

What about the missing grail? Well, the grail was missing for a very good reason; it never existed in the first place. Nowhere in the bible or early Christian writings is there any reference to a holy grail. The grail legend is in fact an invention of early mediaeval literature. It was mainly the work of the author Chretien de Troyes, who set out the first complete version of the Grail legend in his Perceval; the legend of the Grail, written in 1181.

The version that readers are likely to be most familiar with is that in Thomas Mallory’s Le Morte d’Arthur, which contains the familiar story of Sir Galahad and his quest to find the lost grail. So the grail wasn’t in Da Vinci’s painting because it never existed, it was a work of fiction.

Was the phrase San Greal originally rendered as Sang Real? Unfortunately no. In fact the second spelling only appears in a mediaeval translation of the Perceval story by an English monk called John Harding, where the phrase was mistranslated. In every other reference to the phrase it is written as San Greal.

So on to the secret society which, like a hidden code, is a essential feature of any good conspiracy theory. Well, wonder of wonders, both the Order of the Priory of Sion and the secret documents in the Paris library actually exist! Unfortunately, both were created in the 1960’s.

Both the order and the documents are the creation of three Frenchmen; Pierre Plantard, an eccentric crank who believed himself to be the true king of France, journalist Philippe de Chérisey, who agreed to help his friend concoct evidence to support his claim, and surrealist artist Gerard de Sede, who joined in what he saw as a wonderful piece of performance art.

Pierre Plantard (left) with Philippe de Cherisey.The whole story was revealed by another French journalist, Jean Luc Chaumeil, who was given access to hundreds of letters and documents by de Sede’s son shortly after de Sede’s death which set out the whole plan in detail, including drafts of the secret dossier to be deposited in the National Library. It is a requirement of French law that all clubs and societies be registered with the authorities. The Order of the Priory of Sion (named after a hill near Plantard’s home town), was registered in the year of our lord 1959.

Chaumeil contacted the authors of the Holy Blood and the Holy Grail before their work was published and warned them about the Priory of Sion hoax, but in a wonderful example of confirmation bias his warnings fell on deaf ears. The conclusion had already been reached, contradictory evidence was simply dismissed or ignored.

Does it Matter? But we should end by considering a question that is often asked of sceptics; does it matter? Does it really make any difference if certain people are running around believing in flying saucers, the Loch Ness Monster, or alien abductions? Do such beliefs do any harm? I think they do, in fact I think they represent a grievous threat to the future of our society, and risk plunging us into what Carl Sagan called a ‘demon-haunted world’.

The problem is that an openness to improbable claims in one area leaves us very susceptible to improbable claims in another, and not all such claims are harmless. Conversely, cultivating the habit of critical rational thought; questioning all claims, demanding to look at the evidence, weighing up the improbability of the claim being made, and asking if the evidence being adduced is robust enough to support the claim, makes us much more difficult to deceive.

Take, for example, the case made by the British and US governments to support their invasion of Iraq. Both have now acknowledged that there never were any weapons of mass destruction in Iraq, yet both set out a very persuasive case prior to the invasion, a case that convinced many people of the truth of their claims.

All the tricks of the conspiracy theorist were used. Think of Colin Powell’s famous address to the UN; classic pattern-weaving. He adduced a series of facts, then imposed a pattern on them. Confirmation bias was also much in evidence; in various enquiries following the Iraq war the intelligence services of both countries made the same point; they had presented the governments with all the evidence, including that which contradicted the WMD claims, but the governments were only interested in the evidence that confirmed the conclusion they had already reached.

It is not even necessary to believe that the governments in question were consciously misleading us. It is entirely possible that both actually believed the claims they were making, but they arrived at their belief by the same route, and because of the same flawed reasoning, that make all conspiracy theories possible.

This tendency may have even more serious consequences. The most worrying threat facing our species at present, and perhaps the most serious threat we have ever faced, is that of climate change. It amuses me when I hear people say ‘we have to save the planet’. The planet has survived periods when the atmosphere was pure cyanide and the oceans were molten lava. Over 99% of all species that ever lived are now extinct, and when oxygen first entered our atmosphere it wiped out almost all life on earth. The planet has survived far worse than we can ever throw at it. The planet is fine. We, on the other hand, are facing the possibility of extinction as a species if we get this one wrong.

Our demise would be a matter of utter indifference for the planet. As George Carlin put it, the planet will shake us off like a dog shaking off fleas. In a very short space of time in geological terms, say 10-15 million years, there would be no trace of us ever having been here. All evidence of the wonderful products of our imagined superiority would have vanished.
Whatever creatures existed then would live out their lives totally oblivious to the fraction of a second we spent here. The dinosaurs were on earth for some 165 million years, we have been here for barely 200,000. Our arrival and our departure would barely raise a cosmological eyebrow.

As with so many other problems we turn to the United States, the wealthiest, most powerful and most technologically advanced country on earth, and look to them for leadership. We rely on cool heads, on rational thinking and on accurate information. In that context I want to end with a very brief video clip. As part of their program to deal with climate change the US government have established a joint committee of the US Senate to look into the problem; the House Sub-Committee on Energy and the Environment.

At the committee opening in March 2009 the members were each given the opportunity to set out their approach to the issue. This is the presentation of Congressman Shimkus, the Representative for the State of Illinois

I leave you with a quotation from Thomas Huxley: