Alfred Wegener and continental drift: Crackpot or heretic?

It is not uncommon for writers who wish to disparage science to refer to Alfred Wegener and his theory of ‘continental drift’. People laughed at him, they say, and ridiculed his ideas, and they are not laughing now. The establishment saw continental drift as a crackpot theory, or a threat to some existing theory. He was a heretic against the scientific establishment, and did not live to see his ideas triumph. Here is another example of how science is only, or only a little better than, a set of opinions of scientists that can be overthrown at any time. What is called ‘science’ is just the opinion of the majority of scientists in a field, and a plucky loner (Wegener was not a geologist) may eventually overthrow the established opinion and receive the credit he deserves.

This view of science is particularly comforting to religious extremists, postmodernist philosophers and science-deniers of all stripes (climate change, AIDS, vaccines, and so on).

But it’s false (and could not be true in its full-blown postmodernist form in any case, because if it was true, why should the heretic be any more right than the established views?)

Quite recently, Matt Ridley, who used  to be an admired science writer in his own field of biology, invoked Wegener (amongst others) as an example of a heretic who was persecuted by scientists but eventually  triumphed. This is by way of lauding a ‘sceptic’ who Ridley thinks (without presenting any evidence) will one day show that humans are not causing  global warming.

Perhaps I’ll come back to Ridley later. For this occasion I want to comment on Wegener, and I’ll start by stating some facts.

  • Wegener’s theory was taken seriously by geologists, even though they were rightly sceptical.
  • Wegener was not a heretic, because he had nothing to be heretical against.
  • Wegener was not the father of plate tectonics, which is not the same thing as ‘continental drift’.
  • Science was working pretty much as it should in his case. (And I dare say this was probably the case for most of the ‘heretics’ Ridley mentions.)

Let’s consider the state of geology in Wegener’s day, around 1915-30. The world had been mostly mapped, and many geological structures around the world, particularly those of potential economic value, had been mapped too. The main geological periods had been identified, many rock strata had been placed in their correct order and some absolute dates had been obtained using radioisotopes, showing that the world was much older than previously thought, even though the dates were not as accurate as those we have now. The geological discoveries tied in with the paleontological (fossil) discoveries, which were explained by evolutionary theory.

But there were lots of puzzling observations of the earth that could not easily be explained. The apparent ‘fit’ of the outlines of some continents – and, particularly, the rock formations on each side – was just one of them, the one that engaged Wegener.  But there was much more.

  • Why were there mountains, if the earth is as old as was now known? It was known that the processes of erosion of rocks would remove mountain ranges in tens or hundreds of million years.
  • Why are the largest mountains in the huge Alpine-Himalayan and Andes-Rockies ranges?  Why are these ranges made up of sediments – as identified by the fossils in them – that had apparently been deposited in submarine trenches called ‘geocynclines’ tens of kilometres deep? And where are the geosynclines of the present day, and if there are none, why not?
  • Why are there volcanoes and earthquakes, and why are they located where they are?
  • Why do some rocks show glaciation in the tropics and others show tropical life in the polar regions? Did the rocks move, or did the climatic zones?

And so on and on. It’s important to remember that a lot of details we now know were not available then and did not become available till the 1950s and 1960s. One particularly important clue that was missing was that the ocean floors are very much younger than most of the continental rocks, less than about 200 million years old, and were formed by spreading from ridges of volcanic activity, such as the Atlantic mid-ocean ridge. Another important detail that needed to be understood is the structural relationship between the continental shields, the oceans and the mantle beneath  them.

There were actually many theories for some of the phenomena, but nothing that explained it all. In such a case, scientists are right to be sceptical. We tend to consider theories better if they bring together lots of isolated observations into one consistent body of explanation, as evolution does in biology and quantum theory does in physics and chemistry. There was no such thing proposed at that time for geology (evolution dates of course from Darwin’s time and the foundations of quantum mechanics were mostly laid in the 1910s/20s).

Some years ago I was on one of many field trips in the mountains of northern Oman. These offer some of the most spectacular (and visible, given the desert climate) geological displays in the world. Vast sheets of rocks, many of them from the bed of a long-gone ocean, and some of them from deep in the volcanic ocean crust, have been thrust far inland over an older land surface, in some places rucking up  the older rock into mountains thousands of metres high, like a vast carpet on a slippery floor. One of the other participants, an FRS in geology, commented that until the coming of plate tectonic theory the only available explanation for this, and all the rest of geology, was magic.

One thing to remember is that a theory must explain those observations that are, on the face of it, inconsistent with the theory. For example, ‘continental drift’ explains why some facing shorelines approximately fit (for example, eastern South America and south-western Africa) but what about those many shorelines that don’t fit?

Another thing that was missing was a mechanism for continental drift. To accept causal relationships, scientists want to know the exact mechanisms by which one thing causes or relates to another. In Wegener’s own field of meterorology, the underlying physical mechanisms of the weather were already known.  In the early 20th century, lots of fundamental work was going on into how chemical reactions occur (their mechanisms). Nowadays, there are scientists studying the mechanisms of genetics and how organisms develop. Wegener had nothing to offer on these lines regarding how continental drift occurred.

Crucially, there was at least one other theory that seemed to explain the observations and it was probably more acceptable at first than continental drift, although it faded as more evidence came in. That is, that the continents were originally connected, but that the land between them had foundered beneath the sea – perhaps more plausible, in the absence of relevant evidence, than moving continents!  This other theory eventually was disproved by the finding that the ocean floors are of very different material from the continental shelves.

There is a book reviewing the state of earth science around the time of Wegener’s death (J A Steers, The Unstable Earth, 3rd ed 1942, originally published 1932) which devotes many pages to discussing continental drift and the evidence relating to it. Clearly the theory had been taken very seriously but as it was incomplete and had at least one rival theory, geologists were right to be sceptical. In fact (as Karl Popper explained) it is right and proper to be as critical as possible of any theory, as it is the one that survives criticism the best that eventually prevails. No doubt Wegener experienced personal remarks and academic bitchiness, but he probably didn’t receive much worse than other proponents of conjectural theories receive. (Incidentally, the objections to Semmelweiss – another of Ridley’s ‘heretics’ – were probably much to do with his attitude and behaviour towards other physicans).

And what theories the Steers book contains! There are many, covering different aspects of geology, and some of them seem pretty strange to us now. For example, there was a theory that the earth had a tendency to collapse into a tetrahedral form, at the same time creating the force that pushed up mountains. This was based on the observation that the main continental shields of the earth form approximately the corners of a tetrahedron, which we now know (whether it is true or not) is no more than a coincidence and a red herring. Much of the theorising in the book  is based on the suggestion that the earth is contracting through cooling.

The book makes it clear that at that time the evidence was stacking up in favour of continental drift and the theory of land bridges was losing favour. Wegener’s theory is given at least the same prominence of that of a prominent expert on earthquakes, Harold Jeffreys, who proposed that the earth was undergoing thermal contraction.

The mechanism of what would later be called plate tectonics (attributed to Arthur Holmes) is also discussed in the book in rudimentary form – the idea that continental plates are mobile on the mantle beneath them.

Before plate tectonics, geology was a mass of unexplained and puzzling phenomena and various theories were widely debated. It was plate tectonics that brought them all together in one wide-ranging and unifying and satisfactory explanation. This happened in the 1950s and 1960s. I won’t go into it here as there are plenty of places where you can read about it. But plate tectonics is much, much more than just ‘continental drift’. Wegener made a contribution to our later understanding – which he did not live to see as he died on an expedition to Greenland studying Arctic weather (his own research field). But there is no reason to regard him either as a heretic or a victim of unreasonable doubt.

‘How can you deny my experience?’

[BPSDB] A few months ago someone commenting on a blog post (I think it was on Gimpy’s blog) described how some of his family were allegedly cured of illness by homeopathy, and asked ‘How can people deny my experience of this’?

I did not have time to reply on that occasion, but I thought that the question deserved a serious reply, and I considered how I would have replied to it.

To deny or belittle someone’s experience is a serious matter, especially when that experience has been a tragic one (which fortunately it hadn’t been in this case). For example, people who have pointed out the strong evidence that autism cannot have been caused by the MMR vaccine have found themselves accused of being sceptical or uncaring about the experience of the autistic children or their parents, even though that is clearly not the case.

So, if I respond to the homeopathy questioner, ‘no, I don’t think your family were cured by homeopathy’, am I denying his experience? The answer is ‘no’, but the reason is not an obvious one.

I would not deny the experience that the members of his family had the experience of being ill and getting better. As I do not know him personally, I cannot be in any position to deny or affirm it, but I tend to assume that people are telling the truth unless I have evidence otherwise, or unless the stakes are very high. In the interest of discussion, I accept that he had that experience.

Similarly I would not deny that the questioner’s family members had homeopathic treatment for their illness. Again, this is something I am happy to take his word on.

But that is not all there is to the claimed ‘experience’. There is an additional claim that they got better because of their homeopathic treatment. This is not an experience. It is an explanation. Even if the family members were made better by the homeopathic treatment, this explanation cannot be experienced directly.

An explanation is a story we create describing the supposed causes of events or phenomena. An explanation may be true or false, and we may sometimes be able to use our experience directly to confirm an explanation, for example, if we see someone knocked down by a car or shot with a bullet, we may be able to say that the cause of death was the accident or the shooting, and ignore the fact that the dead person had (say) serious heart disease or a brain tumour. But causes are rarely that obvious, which is why in cases of death we expect a doctor to certify the cause of death, with in some cases the need for an autopsy or an inquest.

In science, explanations are called theories. (I am simplifying here, but a scientific theory is basically an explanation for a whole lot of observations). The reason why science exists is that explanations are not obvious, and the most seemingly obvious explanation is often the wrong one. Scientists have to consider all the possible explanations for the phenomena they are studying, and try to weed out the wrong ones by looking for the evidence that contradicts them and shows that those explanations are wrong.

We are often led to the wrong explanations by the fact that we do not have all the evidence. We tend to jump to the conclusion that most pleases us and fits the evidence that we have (or that we are prepared to consider, because very often people ignore evidence that does not fit their preferred explanation).

As an example, watch the TV programme The System by Derren Brown if you get the chance. In this programme, Derren supplies a young woman with correct forecasts on the outcome of a series of races. By the fifth race, she has overcome her scepticism and is willing to believe that Derren has a ‘system’ that enables him to predict the results correctly, and she borrows a lot of money to place on Derren’s prediction for the sixth race…

What she doesn’t know (and apparently does not consider as a possibility) is that she is part of an elaborate version of a scam that is commonly used by share tipsters.The true explanation is simply that the programme team has sent out different predictions to a large number of people, and she just happens, by chance, to be the one who received all the correct predictions for the first five races. There is really no reason to suppose she has better odds than pure chance of winning on that sixth race. The evidence was not available to her (or she did not consider it) to determine the real reason for her winning streak.

Of course, there is a lot more to the programme than that, and Derren is too much of a showman to give all his secrets away. We know in all his programmes that he is keeping information from us. We understand that stage magicians do not really do ‘magic’ (the apparent explanation for what they do) but that if we had more information we would know the real explanation for the tricks that amaze and amuse us.

And yet… so many of us fall for the same ‘trick’ when it is done by nature rather than a magician. We jump to an explanation that does not take account of the knowledge  we do not have (or that we ignore). The questioner in the blog was in the same position as Derren’s ‘victim’ in the programme. She assumed that there was a ‘system’, even though she did not know the full facts and more knowledge tells us that this could not be the case. The homeopathy questioner assumed the ‘most obvious’ explanation, that the homeopathic remedies were responsible for the getting better. But that is not ‘experience’. There are other possible explanations, that the questioner’s experience cannot rule out. Most of these are impossible to discuss without knowing the details of the cases. But the  most obvious explanation is that the patients would have got better anyway without assistance. This is the explanation that homeopathy ignores, but science cannot. It is why science advances all the time, while homeopathy is stuck in a time-warp of ignorance.

To summarise: I do not deny the questioner’s experience that the patients got better, and that they took homeopathic remedies. But that the homeopathic remedies caused the improvement is not part of his experience. It is an explanation. The difference between science and homeopathy is that science is obliged to question this explanation and test it against evidence. Homeopathy does not do this.