Book interview

Occam’s razor and the search for simplicity

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An analysis tool developed by a mediaeval Franciscan friar, Occam’s razor is as relevant today as it has ever been, says author Johnjoe McFadden.

“A lot of people don’t understand science,” says Johnjoe McFadden. “They think it is for scientists and is somehow a different way of looking at the world. But it’s nothing more,” says the author of ‘Life is Simple’, “than looking for the simplest solutions. If you adopt that approach, you are doing science. When you apply simplicity, it becomes science. When you don’t, it becomes something else.”

His book’s subtitle – ‘How Occam’s Razor Set Science Free and Unlocked the Universe’ – invites us to go a level deeper into McFadden’s hugely entertaining “tale of the role simplicity has played in science. It takes the reader through the really big advances by Copernicus, Newton and Galileo, who were all proponents of the principle of simplicity.” The great originator of this idea, the man who according to McFadden in many ways paved the way to modern scientific thought, was the 13th century Franciscan Friar William of Ockham, who hailed from a small village in Surrey. McFadden, who is professor of molecular genetics at the University of Surrey, drives past Ockham on his way to work. After attending a lecture by a colleague attempting to explain why Occam’s razor doesn’t apply to biology, he recalls, “my interest was piqued, and I decided to investigate”.

William of Ockham’s eponymous razor is often misunderstood these days as representing the idea that the simplest answer to any problem is probably the best one. And while that certainly can be the case, Occam’s (so spelt because it derives from the Latin novacula Occami) razor should be more accurately described as a problem-solving principle in which “entities should not be multiplied without necessity”.

We don’t know much about the man himself, says McFadden, and there are plenty of other ‘razors’ (a term in philosophy used to describe rules for the removal of unlikely explanations), but for the author, William of Ockham and his idea combine to create the moment when the world started to think like modern scientists. “The way we think today dates back to mediaeval times. The principle of simplicity was a new light on science. It was a new way of solving problems. It doesn’t matter what those problems are. We use it in mathematics, which of course automatically selects for simple solutions: when you have an equation and you have ‘a’ on both sides of that equation, we cross them out. That’s all mathematics is: a formal way of finding the simplest expression of a problem. It could be as simple as e=mc².”

Put simply, McFadden’s new book is an account of the role simplicity has played in the emerging domain of science over the past millennium, “and you could argue that the pitch of the book from an engineering perspective is: what has simplicity got to do with anything? Why is it important?” The answer to which, says McFadden is that “after years of thinking about it, I think simplicity is the fundamental principle that drives science, making it vitally important in so many spheres of life including engineering. Much of our modern world has been built on the principle of the simplest solutions to problems and that is written into many engineering principles, too, perhaps the most well-known being 'KISS' aka ‘Keep it simple, stupid’.” Engineers, more than scientists, suggests McFadden, realise the importance of Occam’s razor, “because they are more frequently faced with a problem that needs solving: how do I make this machine simpler, or how do I make this machine work with the smallest number of parts?”.

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‘Life is Simple: How Occam’s Razor set Science Free and Unlocked the Universe’

“It is futile to do with more what can be done by less,” wrote William of Ockham, the mediaeval monk who gave his name to the problem-solving principle that, according to the author of ‘Life is Simple’, is as important today as it was when it was invented. 
Back in the 13th century, Occam’s razor shaved away the excess complexity of mediaeval metaphysics, theology and mysticism to clear a way for modern science. So revolutionary was Occam’s razor that it got William into hot water with the papal authorities, and he ultimately stood trial in France on the charge of heresy.
In ‘Life is Simple’, Johnjoe McFadden argues that 21st century scientists routinely employ Occam’s razor in their everyday work, often unaware that they are using it, so ingrained is it in the way we think today. ‘Life is Simple’ is an original and entertaining analysis of the evolution of scientific thinking.

Occam’s razor presents a good fit with modern engineering, says McFadden, but only “because engineering has been derived from Occam’s razor. When engineers created the first steam engines, they stripped away the parts that weren’t needed. Entities should not be multiplied without necessity, so take them out and you’ll get a more robust system. Simple machines are more robust because they have fewer moving parts and have fewer things to go wrong.”

On the other hand, “scientists often miss the fact that they will choose the simplest solution. And I’ve had this conversation with many scientists. I point out that science uses experiments, but so did alchemy. Science uses maths, so does astrology. Science uses reason, so does philosophy. Nothing is unique to science, except that science always opts for the simplest solution. There is no other field of thought or way of thinking that always does this. And yet scientists will say: I don’t opt for the simplest solution – the world’s a complicated place.”

He’s suspicious of the idea that modern thought started with the Enlightenment, the intellectual and philosophical movement that dominated the world of ideas in Europe during the 17th and 18th centuries: “I think a lot of credit was claimed by the thinkers of the enlightenment.” He goes on to say that as a result of this we tend to assume that the first model for the Earth’s axial rotation comes from Copernicus. “In fact, it goes back as far as Ockhamist scholars in Paris, who basically said: 'Wouldn’t it be simpler and make more sense, rather than the Sun and the stars and the Moon rotating around the Earth every single day, to say that it was the Earth that was spinning?' Of course, they were held back by the scripture at this point, which said that God had said that the Earth didn’t move. But at least they considered it. When Copernicus came along centuries later, he made exactly the same argument, but didn’t reference the Okhamists at all.”

McFadden, who describes his professional expertise as being in systems and quantum biology, believes fervently that while it is a commonly held idea that the modernism essentially ‘rescued’ our ancestors from the ignorance of the Dark Ages, “mediaeval scholars like Ockham were making sense of the world around them and they shouldn’t be belittled in any way. It’s easy to look back and say: ‘oh, they believed this, and they believed that and it’s a load of nonsense.’ But they were doing what we were doing, and in a very real sense they became the modern world, and the direction they took was the right direction.”

‘Life is Simple: How Occam’s Razor Set Science Free and Unlocked the Universe’ by Johnjoe McFadden is published by Basic Books, £25.00.


Keep it simple, stupid

In 1934, Albert Einstein insisted that ‘The grand aim of all science [is] to cover the greatest number of empirical facts by logical deduction from the smallest number of hypotheses or axioms.’ Occam’s razor helps us find ‘the smallest number of hypotheses or axioms.’

Nor is the work of Occam’s Razor done. As physics inches its way towards the simplest possible theories, biologists struggle to extract simple theories from the accelerating stream of data pouring out of genomics and other ‘omics’ technologies. It also remains as controversial today as it was in Occam’s time. Statisticians constantly debate its value and significance. Recently a group of French scientists published a paper arguing that simple models, honed by the razor, make better sense of the Covid-19 pandemic sweeping their country than the bulky cumbersome models used by most epidemiologists. At the cutting edge of science, simplicity continues to present us with the most profound, enigmatic and sometimes unsettling insights.

Perhaps most surprisingly, the value of Occam’s razor is not limited to science. Shakespeare insisted that ‘brevity is the soul of wit’ and modernity has taken that principle to heart. From the minimalist music of John Cage to the clean architectural lines of Le Corbusier, the lean prose of Samuel Beckett or the smooth lines of the iPad, modern culture is steeped in simplicity. Occam’s razor is in the advice of architect Mies van der Rohe that ‘Less is More’; computer scientist Bjarne Stroustrup’s instruction to ‘make simple tasks simple’, or Saint-Exupéry’s observation that ‘It seems that perfection is reached not when there is nothing left to add but when there is nothing left to take away.’ In engineering the principle is best known under the acronym KISS, or ‘Keep it simple, stupid.’

Edited extract from ‘Life is Simple: How Occam’s Razor Set Science Free and Unlocked the Universe’ by Johnjoe McFadden, reproduced with permission.

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