Friday 13 March 2020

What is science? Part 4


If we couldn’t learn from the past there would be no science at all. Science depends on the idea that if I do a series of experiments and they all come up with the same result, it is highly likely that they will do so in the future. This isn’t just how science works, it’s how we all behave in our ordinary lives. The problem is that we have to make an assumption that we cannot prove, that the future will be like the past. But because we cannot see into the future, we don’t know that the future will behave as the past did.

This can be illustrated in a number of ways. Every day a farmer arrives to take his cow to milking and to feed it. The cow sees the farmer arrive and says to itself I’m going to fed and milked. But one day the farmer decides that the cow is too old to be milked and sends it to the slaughter house instead. The cow does an experiment every day. When I see the farmer, I get fed. It assumes that the future will be like the past, but instead gets an unfortunate surprise.

In the middle ages there was an example that was used in syllogisms.

All swans are white.
Honker is a swan.
Therefore, honker is white.

It was assumed that by definition swans were white, just as bachelors were unmarried. But the discovery of Australia proved the syllogism wrong, or at least the assumption.

Science depends on the assumption that the past will be like the future, otherwise we couldn’t learn anything, but the most important lesson we learn from the history of science is that science is frequently wrong.

We know that people at various times believed that the Earth was flat and that the sun went around it, but it is not just scientific theories from ancient times that have proved to be mistaken or incomplete. Certain medicines that science thought were safe have turned out to be dangerous. Newtonian physics was superseded by Einstein. Knowledge of the past without which science could not proceed shows us therefore that science has frequently been wrong. The history of science is the history of its falsification. But then if the future is like the past, we should expect future science to prove present science to be mistaken, at least in part. Scientists in the nineteenth century simply could not imagine how Newtonian physics could be in any way less than a perfect description of the universe. They couldn’t predict Einstein, because he was a black swan. But we too cannot predict in what way our present knowledge may be superseded.

The future may in some unpredictable way be different from the past, but even if the future continues to resemble the past it may resemble it in our being mistaken.

From this we should not be overly sceptical about science. It still tells us more about the world and the universe than any other body of knowledge that we have. But we shouldn’t be overly arrogant about science either. Very many able scientists have been mistaken in the past. If the future resembles the past, we can expect very many able scientists to be mistaken now.

Truth is not democratic. It doesn’t matter if the overwhelming majority of scientists think that one particular theory is correct and only a tiny number think a different theory is correct. There have been many examples in the past where a lone voice was correct. Science progresses by theories being falsified. Ordinary scientists of course don’t want to falsify their theories they want to confirm them. They are like the cows waiting to be milked. Every day they confirm their theory. But the herd mentality is sometimes overthrown in a scientific revolution. It needs just one farmer to do that. One rogue scientist slaughters the whole herd and we have a new theory.