Science is all about changing your mind. You have a hypothesis, you test it, it fails, you come up with a new one. This is how science goes: you prove other people (or yourself, in my case  ) wrong. Sure, you "confirm and corroborate" previous findings, too, but you can never be really sure what that means and how much you can rely on these data. The iconic example of Karl Popper was the statement: "all swans are white": no matter how many white swans you see, you can never be sure there isn't a black one out there. But if you find the black one, you definitely know for sure the statement about the white swans is false. That's why the ability to change your mind and admit you're wrong ranks among the most important virtues of every scientist. The opposite is to be dogmatic in the face of overwhelming evidence. Of course, it is not easy to show the humility and admit that we've been wrong. Nobody likes that. It's like kicking a habit: everybody knows it's a bad thing and we need to stop (drinking, smoking, gambling, etc.), but it's hard!

Thus, it's not difficult to understand that people cling to their opinions, even if they're shown to be false. Recently, however, I've experienced how one of my friends was trying to turn this vice into a virtue: he was actually proud of not being swayed by the evidence and called this behavior 'commitment'. He even asked me if I had the same commitment: What had happened?

I left a short, provocative comment at one of the posts of my personal friend on Facebook (who shall be left unnamed), which evolved into a discussion about evolution - it turned out my friend was a creationist. It started with him making the statement I pointed out that by the same scientific process by which US courts convict and acquit defendants of capital crimes, namely by using DNA evidence, we can establish genetic links of relatedness not only between apes and humans, but between all known organisms. Coincidentally, I had just written a post, to which I referred, about recent converging evidence for the 'out of Africa' hypothesis and how it is this sort of evidence, coming from many disparate sources that creationists need to beat.

I told him that I observe evolution every day in my lab. As I work on the fruitfly Drosophila, I see many generations go by in our animals. We make these animals transgenic by inserting different pieces of genetic information to switch certain traits in the brain on or off such that these animals (in those cases where the experiment worked) behave very differently from those without a manipulation. If we don't take great care, the strains where the manipulations are deleterious will quickly evolve to get rid of the manipulation, either by acquiring so-called modifier genes or by getting rid of the manipulations altogether. Genomes are plastic, one might even say semi-fluid: genomes change from generation ot generation, which is precisely what evolution is all about. Evolution is a readily observable, reproducible fact, that's what makes it an object for scientific study. Denying evolution is like denying gravity or radioactive decay or the reaction of hydrogen with oxygen to form water. We know how these processes work with varying degrees of certainty, but we do know that these things happen. So I told him that rejecting evolution means rejecting all of science.

Rather than admitting that he was wrong, he shifted the focus and wrote: Wow, those are two often-used statements which, even if often used, are demonstrably wrong. First, of course, radioactive decay is mediated by the weak interaction, one of the four fundamental forces of nature and if all radiometric dating techniques were so utterly wrong as creationists want you to believe, you might as well give up the standard model of physics altogether. Let's not even start about how well these dating techniques agree with each other and with biological and geological dating techniques.

Second, of course evolution is both a theory and a fact. We observe evolution every day, it's a fact. How it happens mechanistically, is described by evolutionary theory which incorporates some of Darwins ideas but today consists of so many more mechanisms and explanations that I cringe whenever I hear Darwin and evolutionary theory mentioned in a modern context. Darwin is an important, but rather small part of the whole story. More to the point, evolutionary theory explains evolution better than, say, the above-mentioned standard model can explain gravity. Because our understanding of gravity is so poor, we've built the Large Hadron Collider, the world's most complex experiment ever built in human history. So if evolution were 'just a theory', the standard model would be even more shaky and every creationist should believe in intelligent falling. I wonder why they don't?

But rather than admitting he was wrong, he shifted the focus again: I was really glad that he brought up Newton because, as we all know from High School physics, Newtonian mechanics have been replaced by Einstein's special relativity. A great example of how all scientists are forced to change their minds in the face of overwhelming evidence. Newton was realized to be just a special case of what the actual rules are. This is typical of new theories: they explain well what we can already observe and so much more. So I told him that of course Newton has to be 'rejected'. It makes sense to reject old opinions once you've realized you've been wrong.

I pointed out how evolutionary biology increasingly rests on several lines of converging evidence that independently, in different labs, by different people come to strikingly similar results. Now, instead of admitting he was wrong in the face of such overwhelming evidence, he shifted the focus again: I had to laugh: a conspiracy of this magnitude would dwarf even the craziest conspiracy theories: area 51, JFK, 9/11 that's all peanuts compared to tens of thousands of scientists over more than 100 years forging data world-wide in all disciplines of science. He replied I think this is where it dawned on me that all arguments are lost here. He took a great scientist who became famous because he went against common knowledge as an example that science never goes against common knowledge? What? How is it even possible to contradict yourself within a sentence or two and not notice it? If it only takes one individual to turn scientific knowledge on its head, why doesn't it happen all the time? Especially now when the number of scientists has multiplied manifold since the times of Darwin? We should see scientific revolutions on a yearly or even monthly basis. But according to my friend, somehow it's exactly the opposite. Which way is it now, are scientists following the ones with the crazy ideas or are they conservative and never challenge common knowledge at all? I'll answer it for you: scientists follow the evidence.

The funny (and sad) thing is, it gets even crazier: Instead of starting to think that he may be getting out of his depth, he digs himself in even deeper. Now he not only shifts to the completely ludicrous 'great flood' which is basically physically impossible, he also seems to indicate that evidence somehow is a democratic thing. If only enough people voted that the stone will fly crashing to the ceiling, it eventually will. Really, what is there left to say? At this point, if I wouldn't know him so well, I would have used a quote from Thomas Jefferson: "Ridicule is the only weapon which can be used against unintelligible propositions."

But I do like the guy and I still consider him my friend, of course. It is rather sad to see how, like a junky, he is incapable to see that his rationalizations become increasingly irrational, self-contradictory and incoherent. I can only assume that his religious upbringing has brain-washed him so extensively that he, in effect, has become unpersuadable: so convinced of something, that no evidence will ever change his mind. He has become lost to reason and reality forever, caught up in an imaginary la-la land. And as if to add insult to injury, he thinks being immune to evidence and incapable of changing your mind is even a good thing. Never has the word 'commitment' been mis-used so horribly.

Just over a year ago I wrote: "Most likely, there is already an echo-chamber somewhere, where people are using 'unpersuadable' as a positive adjective when describing themselves." I don't think we'll have to wait much longer before we find it.

Personally, one of the most attractive traits when choosing science as a profession for me was that it's not a matter of opinion, nor of politics, nor of perspective: your statements can in fact be clearly wrong. We may never know if they're right (that's bad enough), but at least we definitely know when we're wrong. Creationism is not a matter of debate, polling or opinion, it's simply wrong, just like the statement about the white swans. What we're left with is the best we can currently do.

I was not surprised that after presenting him with so much evidence, when I asked him for his evidence, I received nothing. Once you've left reality, evidence no longer matters. I even asked him why his creation myth of choice, the Biblical one, was in any way preferable to any of the other creation myths, but did not get a single argument let alone a shred of evidence. It was clear to me that creation myths don't stand a chance when you compare the evidence with that of evolutionary theory, but that after so many thousands of years of Christian theology they haven't even been able to come up with a single argument of why one should believe their creation myth rather than some other, is a quite poor track record, especially when you compare it with the scientific track record of the last 150 years alone.