Who should you trust?

It is a simple fact that the world is a complex place. You can't be everywhere and know everything from first-hand experience. And so inevitably you have to accept reports from others about how the world is, and incorporate those reports into your understanding of the world.

But how do you decide whose reports are trustworthy and whose are not? And how do you justify those choices when (also on the basis of second-hand information) others have chosen to trust different people and have come to radically different ideas about the world.

In his comments on Paula Kirby - Believers in denial world. JonJ has quite clearly come to a very different understanding of climate change and its causes from my own conclusions. Neither of us is in a position to do much in the way of verifying the data directly, so both of us are relying on reports from others.

But it is clear that we have chosen to trust a radically different group of people.

So let's have a think about trust and skepticism, who we place our trust in and why.

First, there are some people and some aspects of what they relate which you are able to check directly. So you can develop a view informed by direct evidence as to their trustworthiness and how much weight you can place on their word.

Second, it is possible to make some assessment of a person's character by comparing him or her to others who you know, and in that way make a rough estimate of their trustworthiness even though you have had no opportunity to make any kind of direct check.

Third, you can go by reputation. In assessing somebody's trustworthiness you can rely on the opinion of others who you do trust.

Fourth, you can look at motivation, whether a person has any particular reason to lie on a particular subject, whether they have something to gain by doing so.

Then you can consider, if somebody was lying to you on a topic, whether it is likely that the lie would have been found out by somebody else and word of this reached you.

None of these methods are certain, none are as good as finding out for yourself, but they do allow you to make some kind of assessment of the balance of probability that you are being told the truth.

Let's consider how this might be applied in a case where (if you are not a professional biologist) you are definitely going to have to rely on second-hand knowledge. Let us think about the "debate" between those who accept the evidence for Darwinian evolution, and those who are Young Earth Creationists.

Now, there is a huge amount of scientific evidence in favour of an earth whose age is 4 billion years or so. I shan't go into the details of what it is, that isn't the topic of this post. But if earth is less than 10,000 years old as the Young Earth Creationists would have us believe, then all this scientific evidence must be wrong.

If this is the case, then one and only one of the following three things must be true.

1. Scientists are being entirely honest, but have misinterpreted the data or have yet to discover some decisive bit of evidence which will prove the earth is only a few thousand years old.
2. Scientists are engaged in a world-wide conspiracy to hoodwink us all into thinking the earth is old.
3. The evidence for an old earth is real, but has been put there by God to give the impression of an old earth, and God has done such a good job of it that there is no way for us to be able to see the join.

You'll note that these three options are mutually contradictory. Either the evidence for a young earth exists or it doesn't. If it does, then (3) can't be true. If the evidence does exist, then scientists are being honest about it or they aren't, which means that both (1) and (2) can't simultaneously be true. Creationists don't choose just one of these and stick to it, they slip and slide and slither between these three positions depending on who they are arguing with and what bit of awkward evidence they are trying to explain away.

Let's take option (3) first. This is an unfalsifiable proposition, deliberately designed so that no evidence can possibly be obtained that would decide the question in either direction. It is a variant of the 5 minute hypothesis, and as such can be dismissed. While there is no means of proving it to be false, equally there is no reason to think it is true. The fact that creationists make such retreats into untestable propositions when the going gets tough is a very good reason to consider them untrustworthy.

Let's look next at the idea of the global scientific conspiracy. From what we know of human psychology, it is quite clear that this secret is just too big to keep. If there were such a conspiracy, it would have come out by now. Any scientist who could prove Darwin wrong would have fame that lived down the ages. Too much of a temptation for such a secret to have been kept among so many scientists for so long. It would never have lasted. So the conspiracy idea just isn't plausible.

Lastly, let's look at the idea that the scientists are honest but mistaken. For this to be true, dozens of entirely independent bits of evidence which all point the same way would all have simultaneously to be wrong. Radioactive dating techniques would have to be wrong, geological evidence, continental drift, astronomical and cosmological evidence, physics, biology. All would have to be giving wrong answers, and moreover, entirely by chance all be giving the same wrong answer. This isn't plausible either.

So even if you don't understand all that much about evolution, you can safely trust the word of the scientists on this one. The earth is billions of years old, time enough for Darwinian evolution to have done its work. Darwin was right, though there are always more details to be learned about it.

So lets look next at the issue of man-made climate change, about which JonJ and I had our disagreement. First of all, I will accept that the evidence for man-made climate change is not as strong as the evidence for an earth that is billions of years old. But it is still pretty strong. And it is possible to make an assessment using the same principles. We can still consider a number of possible hypotheses as to how the present situation might have been reached even through man-made climate change doesn't exist.

1. The scientific consensus is mistaken, and although the evidence for man-made climate change appears to be strong, it is in fact being honestly misinterpreted. Either climate change isn't happening, or it has other predominant causes unrelated to human activities.
   
2. There is a worldwide conspiracy of scientists to hoodwink the world into thinking that climate change is man-made when it isn't.

Again, note that the two options are mutually contradictory. A scientist can be dishonest, or can be honestly mistaken, but he can't be both at the same time. you have to choose between the two options.

Let's consider the conspiracy theory first. For this to be true, it would have to be a big secret. Again, too big to last. Peer review is part of the scientific culture, and the discovery of scientific hoaxes such as Piltdown Man is part of scientific folklore. It is not impossible for individual scientists to be dishonest, but the scientific method, with its peer review, repeatability of experiments and cross-checking of different methods against each other is in effect a vast exercise in institutional mistrust designed specifically to ensure that such dishonesty (as well as more mundane mistakes and errors) are brought to light eventually. I've described a bit of the scientific method in a previous article The conflict between science and religion.

Scientists know this, and so the motivation to deceive mostly isn't there, not least because of the near-certainty of being found out eventually. So, broadly speaking, we can rule out a scientific conspiracy as a plausible option.

But what about Climategate? Well, I've read a selection of the emails, and they don't form evidence of a conspiracy. What I have noticed is the following

• It is perfectly clear that those who have released the emails have been very selective about what they have released, and have deliberately chosen the ones which are potentially most damaging. This is called cherry-picking, highlighting the evidence that best supports your case and hiding the rest. It is unscientific and dishonest, and should be taken as a sign of dishonesty on the part of the hackers.
• Much of what is in the emails concerns techniques for understanding the data. For instance, tree-ring data offers a good proxy for temperature, except in the last hundred years or so. We know that it is a good proxy in older times because there is a good correlation between that and direct human temperature measurements. But in the last hundred years, tree rings in industrialised counties are thinner than one would expect. This is likely to be caused by industrial pollution. It can't be caused by lower temperatures, because we can measure the temperature directly and we know what it has been these last hundred years. So the "decline" in temperatures as supposedly indicated by the tree ring data has to be discarded, because we know it is wrong.
• Scientists are human and intemperate just like the rest of us. Few of us would look all that good if the entire contents of our private emails were suddenly and without warning made public. The UEA scientists are learning the hard way something I've known for a while. If you write something down, even in private, you have to be prepared to defend it in public.
• It is necessary for scientists to discuss incomplete, provisional and ongoing work amongst themselves. The unpublished material needs to be gathered together into published papers, where the necessary calculations have been checked, the data has been peer-reviewed and the conclusions justified. Scientific papers are published in such a way that other scientist can replicate the work and see if they obtain the same results. To treat informal unpublished material as if it is a scientific paper and then claim it is incomplete is unreasonable.

So, while Climategate might be evidence that some scientists don't much like each other (an all too human trait), it is not sufficient to justify a belief in a conspiracy theory.

So what about the idea that the scientific consensus is honestly held but wrong? It isn't impossible that this is the case, though it seems unlikely. What uncertainty remains is not about whether we are changing the climate, but rather how fast and by how much we are doing so. The only way to resolve that uncertainty is to do more science and get better answers.

But in the meantime, we need to go with the best guess that the evidence suggests. Our best guess is probably better than a second-best guess that ignores the balance of the evidence. And our best guess suggests that we need to take action now. That will be as much of a discomfort to scientists as the rest of us. In fact, it is worse for scientists - nobody likes to be the bearer of bad news. The scientists would have much preferred to be able to say there is nothing to worry about - they could stop worrying as well.

Talking past each other

It seems to me Creationists and other religious people who hold fast to Biblical authority seriously misunderstand science and scientists. They appear to think that scientists think the way they themselves do, and that scientists are engaged in anti-Christian religious warfare, with Darwin as their God and The Origin of Species as their revealed holy text. In essence, they think of atheism as a religion just like their own.

But at the same time, they see that science has been very successful in describing the universe, and they want some of the prestige of science to rub off on them. Knowing that scientists do rather go on about getting evidence, they assume that all this evidence is carefully selected in order to make the scientists’ theories look better. It simply doesn’t occur to them that scientists work on the basis that theories should be made to fit the evidence (including the inconvenient bits), rather than that the evidence should be selected to support the theory.

So the religious people try to act like scientists, or at least try to act the way they imagine scientists do. They go round cherry-picking bits of evidence, for instance trying to explain how the dinosaurs all perished in Noah’s flood, or how (based on selective quotation) they try to persuade people that scientists think that “fine tuning” of universal constants is a proof of God’s existence.

On the other hand, the incomprehension that the scientists labour under is almost as great. They have for the most part been so long in the scientific habit of thought that in many cases it doesn't even occur to them that somebody can function quite adequately based on a profoundly unscientific way of thinking. They often make the mistake of thinking that the religious types must be stupid, in that they can't comprehend the evidence that has been amassed. It doesn't occur to them that the religious types think differently, that the religious genuinely think that the scientists also think religiously, and that the religious simply prefer to accept the bits of evidence that support their own case.

The overall effect is often a dialog of the deaf, because neither side properly understands the thought-processes of the other. If you review many of the comment threads on CiF, you will find this mutual incomprehension demonstrated many times over.

If the scientifically-minded people are going to get the religious to understand them better, it is going to be necessary to go back further than a mere recitation of the evidence in favour of this or that scientific theory. That kind of recitation certainly isn’t going to be enough to persuade religious opponents of evolution of anything at all concerned with natural selection.

What is needed is a description of how the scientific method actually works, and of the principles of how scientific discoveries were made and checked. When I studied science at school, we were taught none of this. We were taught the results of science, not the processes of science. The question of how we can tell that we really know what we think we know simply wasn’t touched on in my day. I’ve picked that up in the course of reading since I completed my formal education.

My children have been through the school system rather more recently, and I was very heartened to see that much more emphasis is now put on this issue. I suspect that it could in principle be handled even better in schools than it is now, but there is at least definite progress in the right direction.

So, if you find yourself in a debate with a religious person who seems not to accept scientific evidence, I suggest you start talking instead about the scientific method and how theories are made to fit the evidence. Darwin himself spent about 20 years acquiring evidence before he felt able to publish On the Origin of Species. Be inspired by his example to explain this to others.

(This article was offered to the Guardian some weeks ago, but not accepted. It seems that Andrew would prefer to claim that no atheists have any interest in understanding the religious rather than publish an article which attempts to promote that understanding.)

The conflict between science and religion

There’s been a lot of public discussion about the conflict between science and religion, whether there is one, and what it consists of. I think it might be worth looking at this in some detail.

First of all, I’d like to describe a bit about science, what it is and how it works. The press tends to report science much as it does politics - looking for disagreements and arguments between authority figures who can be persuaded to say uncomplimentary things about each other, and each of whom will defend their view in order to persuade others. The problem is that science isn’t actually like that.

Scientific theories are descriptions of the way the world works. You start with observations. Let’s take a very simple example. You notice that when you throw a stick up in the air, it falls to the ground again. No matter how many times you throw it up, it always seems to come down again. So you generalise this into a theory.

What goes up, must come down.

Although it is expressed in a very primitive fashion, this is in fact a respectably formed scientific theory. Other people can also throw sticks in the air and see if they come down for them. They can also try with other objects, such as stones. If they all come down, that is said to confirm the theory. If any of them don’t, it disproves it.

Now, suppose on some occasion, you throw a stick up and you don’t see it come down. Must the theory be changed? Not necessarily. There are various possibilities that you have to eliminate first. The most obvious one is that you lost sight of the stick and didn’t see it land. Or perhaps it got stuck up a tree. These sorts of problems are what scientists call measurement error, and it happens frequently, in fact far more often than truly new results that disprove existing theories.

Once you have established that your theory is probably correct by throwing lots of sticks, stones and other objects up in the air and seeing that they do come down, you can try to refine it. For instance, you can ask how fast do things come down? So you vary the experiment, you throw things up with different amounts of force, and measure how high they get and how long it takes for them to return to the ground. After doing this enough times, you are able to work out that the acceleration is constant, and is about 9.8 meters per second squared. In other words, every second, the downward speed of the falling object increases by 9.8 meters per second. This means that for instance if you know the speed with which a cannonball comes out of a cannon, and you know the upward angle at which it is fired, you can predict pretty closely where it will land. That is quite a useful thing to know in battles. And as it happens, Galileo, who famously dropped two different-sized lead weights off the top of the Leaning Tower of Pisa in order to demonstrate constant acceleration, wrote artillery manuals that would predict the fall of shot in this way.

But very light objects don’t seem to behave the same way. Balloons and feathers fall far more slowly. What of them? The number is no use if you can’t tell what objects it applies to and what objects it doesn’t. And so you have to start taking into account air resistance, and work out how much that affects the figures. And so on.

This is a very simple example, but it describes exactly what science is about. You make observations, and get your theories to fit them. And if you then get observations which aren’t predicted by the theories, once you have eliminated the possibility of measurement error, you have to change the theory.

That is why, whenever an experiment is reported in a reputable peer-reviewed scientific journal, there is a very specific format that has come to be used. First you describe what the experiment was intended to test. Then you describe your methods, how you went about testing it. Then you describe your results, and finally you offer any hypotheses that you think could be generalised from the results.

This separation has a very particular purpose. No scientist expects his word to be taken on its own authority. Scientific papers are written specifically so that others can repeat the experiment and see whether they get the same results. They can also look at the methods and may point out some measurement error that the original scientist didn’t think of. Or somebody might think of an alternative theory that explains why the results are the way they are. The scientist writes everything down that he or she can think of that might mean the experiment is wrong. Scientists are of course human, and don’t always manage to meet this high ideal. But this is what they aim for.

Now where does the conflict with religion come in? First let’s explain what the conflict is not. This is not about hordes of atheist scientists who have discovered evolution as the new religion, appointed Darwin as their prophet, chosen The Origin Of Species as their sacred text, and have declared war on all competing religions. That is the old religious way of thinking, and if you have understood anything at all of what I have written above, you will realise that scientists don’t think that way.

In practice there are two parts to the conflict. First is the business of always starting from observation. If you have no observations, you have nothing to make a theory about. As a result of scientific discovery we have learned that many things previously thought to be the work of God intervening in the world to enforce his sense of morality are in fact the result of natural processes. We have learned that many diseases are caused by germs, and that antibiotics work to cure them irrespective of whether the person being cured is a sinner or righteous. We know the cause of lightning, and that a lightning conductor works just as well on the roof of a brothel as on the spire of a church. These answers seem to conflict with what religion has told us.

The thing is, in all these observations and discoveries, we do seem to be a bit short of actual sightings of God. That means that science can’t really offer any theories about God, because we have no observations on which to base theories. Every time a scientific discovery has been made in an area previously thought to be evidence of God working in the world, it has turned out that the phenomenon can actually be explained by the consistent operation of unchanging natural laws. There hasn't been a single case where the scientists have concluded "Oh, it turns out that this is God working in the world after all".

The other part of the conflict is the question of testing and cross-checking. Scientists are trained not to accept each other’s authority. They want to check the evidence by trying things out for themselves and seeing if they get the same results as each other. This can get very complicated. For instance, human beings are very complex and varied, and don’t always react in the same way to things, and so your results have to take this variability into account if you are testing things like whether particular drugs work to cure a disease. Almost all the complexity of modern experimental science is in trying to get rid of measurement error and cope with this sort of variability, so we can be sure that we really know what we think we know.

Religion works in a somewhat different way. The most important is that you are not supposed to check things, you are supposed to accept them as a matter of faith, and that holding fast to this faith is regarded as a good thing of and for itself. Several passages in the Bible say words to the effect of “Do not put the Lord your God to the test”. This is absolutely the complete opposite of the way scientists think.

Some religious people, seeing that scientists have gained a lot of prestige in terms of having their explanations of the world accepted by the public, have decided that they ought to try offering what they think of as scientific evidence in support of biblical stories. Unfortunately, again they are thinking in the opposite way from the way real scientists think. They start with a Biblical story (e.g. of Noah's Ark) and develop a theory from it (e.g. that there was a worldwide flood). Then they look around for evidence that supports the theory and carefully ignore anything that offers an alternative explanation. So long as they use lots of long sciencey-sounding words and write papers with lots of impressive-looking footnotes, they can fool quite a few non-scientists into thinking that they are doing real science. But it isn’t so. Real scientists start with observations before forming a theory, and if some observations don’t match the theory, they don’t cherry-pick the ones that fit and ignore the rest. As a scientist you have to deal with the inconvenient observations as well as the ones which gave you the result you expected.

The conflict gets at its sharpest when considering what should be included when teaching science to children. Scientists, not unreasonably, want science lessons to be about the finding-out process of real science. Some religious people want the pseudoscience that is designed to support their religion included instead, and for this to be accepted on authority.

The crux of the conflict between science and religion is the conflict between evidence and authority.