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Posted April 22, 2001

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One of the favourite themes in science over the last two thousand years has been the contradiction between science and religion.

In fact, you could say that one of the traditional ways for scientists to fail, and even die, has been at the hands of religious figures and religiously-motivated governments. Being killed, for publishing ideas that contradict the status quo, ranks up there with: getting brain damage by touching the wrong chemicals; or getting radiation poisoning by spending too much time too close to the wrong atoms.

One of the best known stories in this vein, is that of Galileo. In 1632, he got into serious trouble with the Pope. He had published a dialogue about the solar system, which made too strong a case for the Copernican view. At the time, of course, the Earth was the centre of the Universe. The same Pope had agreed 9 years ago to allow Galileo to write about the system Copernicus had proposed, with the Earth in orbit around the Sun -- but only if it were presented in a purely hypothetical light. Galileo was not careful enough, and under official threat of torture, he was forced to take back what he said about the Sun, and got away with living under house arrest for the rest of his life. That light sentence was an accomplishment in itself, under an inquisition that would burn you at the stake for heresy, even if it meant digging you up after you had already died.

Galileo also narrowly escaped trouble with the Pope over atomism, which is an idea that comes from ancient Greece, proposing that matter is composed of small indivisible parts. Supposedly this view was incompatible with the transformation of bread and wine into Christ's flesh and blood.

A more recent example of troubles between scientists and churches, is the story of Charles Darwin and the theory of natural selection. More than 130 years after The Origin of Species was published, it is just as widely accepted as any other scientific theory, but people are still going to the US supreme court to argue that natural selection can't possibly explain the origin of species. Or, even if it can, at least it shouldn't.

I'll try to give you a rundown of the usual arguments, and maybe some more history, but as always you'll have to sit through a short music break and think about it yourself first.

As always, you can call me in the studio at 352-3706 if you have any comments about the show, or if you'd like to suggest a topic for a next week's show.


Charles Darwin called it the "great principle of evolution." Contrary to popular belief, Charles Darwin did not invent the idea of evolution. By the time he arrived on the scene, the debate about evolution was already in full swing. What he did invent was a reasonable mechanism by which evolution could occur, which he called "natural selection."

Artificial selection is what farmers do with their crops and livestock. They keep the best individuals in each generation, knowing that the next generation will be better if they are bred from the best available stock.

Natural selection is what happens if you take away the farmer, so nobody is there to decide which individuals are "better" than the others. So the next generation is mostly bred from... whichever individuals in the previous generation produce the most offspring. And of course, in order to produce any offspring at all, those individuals had to be pretty good at basic survival skills. This is where the term "survival of the fittest" comes from. How "fit" you are is basically determined by how many babies you can have before you die.

Darwin spent years collecting various sorts of evidence indicating that this process is capable of producing various species and varieties of plants and animals. And this is where we start to get in trouble with the Church. You see, God made all the myriad forms of plants and animals. And of course, God made man. And man is different than all the plants and animals. Yet here we have Charles Darwin, saying that natural selection made all the plants and animals. He was very very very careful not to say anything about humans in The Origin Of Species, but later he did write a book later called The Descent Of Man...

Just like those people who thought the Earth was round, and the people who thought the Earth orbits the Sun, Charles Darwin wanted us to think that God was less powerful, or favoured us less, than had previously been thought. Or at least that's how it looked at the time. Darwin was being heretical in the same way as Galileo had been 200 years earlier. Fortunately, Darwin didn't have to worry about torture; but I gather he was rather frustrated that so many people rejected his theory merely because they didn't want it to be true.

Darwin's thinking was obviously influenced by a geologist called Charles Lyell. Lyell was a proponent of the "vera causa" idea, which is that scientific theories should only rely on forces and processes that we can see happening now. For example, whatever caused mountains, rivers, and lakes to exist in the first place, must still be happening now. It doesn't help our understanding of the Universe to propose some miraculous event, which made things become way they are, and which will never happen again.

This philosophy is bound to get you in trouble when it comes to the origin of species.

In the 17th century, one of the popular reasons to believe in a Creator was summarized as follows:

Open up your wristwatch, and look at all the tiny gears. They are all exactly the right size and shape, and they consistently move at the right speed. How did this happen? Obviously, the watch was designed by someone. It would be ridiculous to say that the watch just happened to exist, that nobody designed or created it. Who created it? Obviously, it was an intelligent person.

Now look in the mirror, at your own eyeball. Look at the tiny muscles, veins, and lenses. The eyelid. How did this happen? Obviously, the eyeball was designed by someone. It would be ridiculous to say that the eyeball just happened to exist, that nobody designed or created it. Who could have created the eyeball? It could only have been God.

Now here is Charles Darwin, essentially telling us exactly how eyeballs came to be so complex and beautiful, without invoking the powers of a divine Creator. A hundred years ago, this was just as hard to swallow as it was 400 years ago to accept the idea that the Earth was not the centre of the Universe. In both cases, it provoked a feeling that we had been fooled into believing in a divine Creator.

Fortunately, that's not necessarily true. If you believe in a Creator for reasons A, B, C, and D, and then someone explains to you that reason A is invalid, that doesn't mean there's no Creator. However, it does mean that within a hundred years, most people will stop citing A as their reason to believe in a Creator.

Of course, I admit that a couple of people did come to my door a couple of weeks ago, and they really didn't want to give up on reason A. They had a big list of examples of things that Darwin's theory doesn't explain, and they seemed to think that meant it was wrong about the things it does explain.

But before I get myself in any more trouble, I should get back to Galileo, and explain why the sun sets in a different place depending on the season.

Pick up a pen. Or a pencil. Doesn't matter, you won't be writing anything.

Hold your pencil pointing straight up. Imagine that it's the axis of the earth's rotation, and the earth is spinning counterclockwise as viewed from above, as it always does. Keep it pointing straight up, but move it around in a circle as if you were using it to stir a big pot of soup. Imagine that the sun is in the centre of that circle. You've got the earth rotating on its own axis, and in orbit around the sun. You can see already why it's hotter at the equator; simply because the equator is pointing directly at the sun. The north pole only gets a sidelong view of the sun.

A university professor once told me that the seasons are caused by the fact that the earth's orbit is not circular. Sometimes it's further from the sun, so sometimes it's cooler. That can't be right though, because then the seasons would be the same in the northern and southern hemisphere.

I had to remind him that the earth's axis is not straight up and down. Tilt your pen a little to the left, but keep moving it in the same circle. Now you've got it. When the earth is on the left side of the sun, the southern hemisphere gets more sun. When it's on the right side, the northern hemisphere gets more sun. There you go! Seasons!

Copernicus and Galileo were right!