Occasional Address at University of Sydney Graduation Ceremony

Tim Bedding (April 2011)

Congratulations on finishing your degrees, you deserve to feel proud of your achievements. And well done to your families and friends for putting up with you these past few years.

I am supposed to say something wise and inspiring as you head off into the real world. One problem is that, as you heard in the introduction, I have been here in this university (apart from a few years in Germany) since leaving high school. I've never actually been out there in the real world myself, so I'm not sure there is anything useful I can tell you. Please let me know what it's like! Of course, some of you are not going yet. You are continuing with other degrees in an attempt to delay the inevitable. Maybe some of you will succeed, as I have, in spending your whole lives within the walls of this sheltered workshop and avoiding the real world altogether.

So what should I talk about? I was told to choose any subject I like, so long as I don't talk for more than 10 minutes. Well, what we have in common is science, so I had better talk about that. The good news is that I can't recall anything that was said at my own graduation, so I don't have to worry that any of you are going to remember what I say today. So I can even be a bit controversial, since there's no way I can get into trouble.

Lately, the word "science" is appearing a lot in the news. Even our political leaders are using the word. Prime Minister Julia Gillard said, "I'll be taking my science from the CSIRO, not the radio shock jocks." And Opposition Leader Tony Abbott said, "I think that the science is far from settled". They're talking about the reality of climate change, of course.

We are trained in science, so what are we to make of the debate? On matters of science, I hope we can all agree to ignore the radio talk-back hosts. But which scientists do we believe? They don't all agree. The majority say one thing (climate change is real and largely a result of human activity), but a minority disagree. Do we accept the majority just because they're the majority? Shouldn't we check for ourselves? We're educated in science, it can't be too hard to figure out who is right, can it?

Let's try. We know that carbon dioxide and methane absorb infrared radiation emitted by the Earth and stop it escaping into space. This acts like a blanket and keeps the Earth warmer. Surely we can work out how much carbon dioxide has been put in the atmosphere in the last century and see if it would have an effect. But wait, a lot of carbon dioxide gets absorbed back into the oceans. It's starting to get complicated. OK, that's good - maybe the extra carbon dioxide produced by mankind will dissolve and we don't have to worry about it

How much dissolves? It depends on temperature: hot water absorbs less than cold water. Oops, now we have a feedback loop, but which way does it go? Increasing carbon dioxide in the atmosphere will increase the temperature of the Earth and the oceans, which will reduce the amount of carbon dioxide held in the oceans, which will increase carbon dioxide in the atmosphere. So that seems bad. But how bad? There are other factors. For example, the ocean is stratified into layers of different temperatures. There is a lot of biological matter (living and dead) that absorbs or emits carbon dioxide. It is complicated! And we have only just touched the surface of the science.

The moral of all this is that the science of climate change is complicated. This is true of many subjects. You have spent several years learning in quite a lot of detail about a small part of human knowledge. Looking back, don't you agree that things are actually quite complicated? Maybe that's why they made you study for 3 or 4 years for that piece of paper you just received.

So we should be wary of those claiming to be certain of anything, especially if they have not spent a long time looking into it. But what can we do. We can't all spend years studying this stuff. I think that all we can do is trust the scientific process. That centres on peer review, which means every paper published in a reputable journal is reviewed (usually anonymously) by other experts. This process usually works well. Occasionally it doesn't, but I find it very unlikely that there has been a great swindle and con-job, as some of the skeptics have argued.

Okay, so much for climate change. That was a bit controversial, but my ten minutes aren't up yet, so let's push on. I've been reading a book by Sam Harris called "The Moral Landscape". He looks at the question: does science have anything to say about morals? About what is right and wrong?

Many would say no. Science tells us what the world is like, how it works. For example, are carbon dioxide levels increasing and are they causing a rise in global temperatures? Science is the only way to answer these questions. But many would say science cannot tell us whether a thing is right or wrong. Science has nothing to say on the subject of human values. For example, whether slavery is right or wrong, whether research using embryonic stem cells should be allowed, whether same-sex couples should be allowed to marry and raise children. Most people would say that science has nothing to say on those sorts of questions about human values.

Sam Harris disagrees. He argues that scientists have been reluctant to take a stand on moral issues. There are lot of details and arguments in the book that I don't have time to go into. But I do want to look at the question of why scientists have been reluctant to take a stand on moral issues. But do I dare? For it involves the "r" word: "religion". Oh, what the hell, we've already decided none of you are going to remember this anyway, so let's press on.

The reason why scientists have been reluctant to take a stand on moral issues -- to tell people what is right and wrong -- is that this is supposed to be the domain of religion.

As Sam Harris says: "The underlying claim is that while science is the best authority on the workings of the physical universe, religion is the best authority on meaning, values, morality, and leading a good life." He argues that this is not only untrue; it cannot possibly be true.

So we come to the final thing I want to talk about: are science and religion compatible? Clearly science and religion can live side by side. There are many scientists who are religious (although the fraction is far lower than in the general population). I have a close colleague -- another astronomer -- who is an example.

Science and religion do appear to be compatible. A great many scientists believe in God with no sense of internal contradiction. But Harris says -- and I agree with him -- that this apparent harmony does not stand up to closer examination. The religious scientists either haven't thought things through properly or are deceiving themselves in some way. And the rest of us are usually too polite to point this out.

So at the risk of being seen impolite, let me forge ahead. The difficulty is to understand how conventional religious views are compatible with a scientific view of the world. By "conventional religious views" I mean believing in a supernatural creator who can bypass the known laws of nature to grant miracles, who cares about each and every one of us, even down to what we eat, and who will grant some of us life after death. Is believing those things compatible with modern scientific thought, with all its requirements for evidence, experiment and verification?

Again, Sam Harris puts it very succinctly: "The core of science is not controlled experiment or mathematical modeling; it is intellectual honesty. It is time we acknowledge a basic feature of human discourse: when considering the truth of a proposition, one is either engaged in an honest appraisal of the evidence and logical arguments, or one isn't." (Letter to a Christian Nation)

I am not expecting to change anyone's mind on the basis of this short address. That would indeed be a miracle! But this is the Great Hall of a great university and so it seem as good a place as any to start this sort of discussion. It would be great if these words caused some of you to think about these things, both science-and-religion and climate change, and discuss them. They are surely very important questions.

Now go and enjoy the rest of your life out in the real world, try to make a difference in it, and don't forget to tell me what it's like out there. Thank you.