The Experimentalist’s Apprentice

William of Occam, who is not impressed by this post. Or by anything.

There is a rule in science that says you should assume the simplest explanation that fits with what you observe. This is named Occam’s Razor after the medieval monk William of Ockham, who, it is generally agreed, didn’t come up with it, and was probably talking about something different altogether. It’s central to how we know anything at all about the world, whether in science or in everyday life.

For instance, I just looked outside my window and saw the street. I assume that that’s because the street is actually there. It could be, instead, that my window was replaced with a huge realistic flat screen TV. Or maybe my visual cortex was replaced with elaborate street-rendering software. But using Occam’s Razor, I chose to go with the simplest explanation.

When we look at the track record of Occam’s Razor in science, though, it seems pretty bad. After all, everything is really complicated! If you assumed everything had the simplest possible explanation consistent with the data available at the time, you’d be proven wrong very quickly.

Say you came up with this idea for the tiniest indivisible particles that make up both protons and neutrons and you decided to call them quarks. The simplest theory you can make is that there are two kinds of quarks and you need them in different proportions for protons and neutrons. That is enough to explain why protons and neutrons weigh the same, but are otherwise quite different.

And yet here is what we currently believe about quarks: there are (at least!) six flavours of them, each of which comes in three colours, and all are available in the antimatter variety as well. And even this is not necessarily the whole story – it’s just the simplest thing consistent with what we know *now*. So why do we stick with this method in science, just to be proven wrong?

To me, one convincing explanation is that it is so commonly effective in our daily life that we are conditioned to use it. Anthropologist Mark Collard calls it the flying carpet test: you take the plane to get somewhere because you have experienced it working to get from place to place. You could choose to believe that the flying carpet is more effective, but try to act upon that belief and actually get to your destination!

Occam’s Razor, in daily life if not always in science, often means trusting your experience and your senses. And we go through with it, because though it may not be absolutely foolproof, if you *don’t* trust your experience and your senses, it’s very difficult to come up with anything on which to base your beliefs at all.

Very difficult, but not impossible. For example, you could organize all incoming information to fit with some theory you really like. People who do this are called conspiracy theorists. Their theories are often considered silly precisely because they are never the simplest, clearest available explanation. But in another way, conspiracy theorists are actually radical Occamists – the belief that everything is connected to one big explanation is a simplifying tool of its own.

The aphorist Igor Yuganov had a joke theory during Soviet times: the United States didn’t really exist, it was just invented by the KGB to root out dissidents. The KGB is a notoriously shady organization, so if you have to believe in something strange to stick with the idea that the US is a KGB plot, it might well actually be worth believing. On one hand, it’s not simple: you have to explain away lots of things, like mail from the US, the moon landing, and hamburgers. On the other hand, what could be simpler than having one explanation – the KGB – for absolutely everything. A lot of conspiracy theories work like that.

So are conspiracy theorists using Occam’s Razor, or not? Upon looking at it closely, it turns out what simple means is not a simple question at all. The thing I cannot understand is not whether to use the simplest explanation, but what the simplest explanation actually means.

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6 Responses to The Experimentalist’s Apprentice

  1. Mila says:

    Мы пытались найти наиболее простое объяснение исчезновению моих лыж на Silver Star и появлению других взамен основываясь на тех знаниях, которые у нас (якобы) были… Выяснилось, что знания, которыми мы обладали “в данный момент” были неверны. Не знаю, к месту ли комментарий, но это то, что пришло мне в голову. А вообще интересно 🙂

  2. Simple usually means ‘intuitive’, but in a scientific sense it must also mean ‘minimal’. With new information refuting an old theory, a scientist will try to come up with something like a tightly wrapping ‘convex hull’ around the (old and new) facts. A scientists’ new theory will probably explain why forces at the micro-scale behave so strangely, but not why the poor get poorer and the rich get richer. Conspiracy theorists rely on their intuition, and usually their explanation is something non-verifiable, loosely fact based, but very intuitive and easy to explain. It is the opposite of minimal, and thus instantly appealing for its universality. It’s the sort of uninteresting cop-out explanation that appears at the end of convoluted creative writing exercises. And then he woke up.

    • zolltan says:

      That’s a really good point about intuition being connected to simplicity in everyday life, but not in science.

      But I think you’re wrong when you say “simple” in science means minimal and not universal. Being universal is an important criterion – explain the most with the least. This is, at least, how it is in the canonical story of the Scientific Revolution: the reason Copernicus went with heliocentrism was not because geocentrism couldn’t explain the facts – it was because geocentrism required a lot of explanations that were “minimally” added to the previous set of explanations one at a time, whereas heliocentrism was one underlying idea.

      Similarly, “and then he woke up” sounds to me like a *very* scientific assumption to a bunch of bizarre shit happening. Which is why scientists shouldn’t write surprise ending short stories.

      I’d also like to clarify what you mean when you say science won’t explain why the poor stay poor and the rich get rich?

      • If you allow “Everything should be kept as simple as possible, but no simpler.” to be an adequate summary of Occamist views, the latter part is what I’m trying to get at. “But no simpler” is open to interpretation, but I see it as the opposing force to conspiracy theorists.

        So science can explain why the poor stay poor and rich get rich, but it is unlikely to be related to a theory about fundamental forces.

        I’m not against universality, but one of the main points of science (in this engineer’s view :P) is to produce theories that are applicable to real life. Overly universal theories tend towards conspiracy, and are too simple to be useful.

        Do you agree?

        • zolltan says:

          Tell that to the string theorists (I suppose that might be part of your point).

          Still, string theory may be many things, but it’s not a conspiracy theory. And, coming at it from the other way, one of the beautiful things about science is the application of laws or technologies in unexpected places. Like seeing Price’s Equation in empire building (an example I bring up because it’s super cool and also something I talked about earlier on this blog or using simulated annealing for financial calculations. It seems to me conspiracy theories are not necessarily more universal – they are just in a different domain. A theory of particles isn’t going to explain the actions of the US government, but then a theory of lizard people isn’t going to explain the results of the LHC. There are better ways to distinguish science from conspiracy theory than simplicity.

          And “no simpler” doesn’t do much for me just because it seems so post hoc. You can only tell if something is too simple by checking and seeing it doesn’t work. And “correctness” is not a useful characteristic because presumably that’s the question people disagree on when they’re discussing some theory.

          At the same time, when I wrote the post, it wasn’t meant as a complaint that I could not identify conspiracy theories. Instead I was trying to figure out how to classify “simple” and I think on that point your idea of using universality to distinguish different kinds of “simple” is a great one. Within the realm of “simple” explanations, and given the same set of “facts”, we can set up a classification scheme based on whether a given fact is used as input or instead an explanation for that fact is an output.

  3. Pingback: Please Assume I Don’t Know Things, But Believe Me If I Say I Do | Rated Zed

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