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.