Monday, January 17, 2011

Mailbag Monday: Occam's Razor

Mailbag Monday: A weekly segment that covers readers' questions and concerns about all things Philosophy, Bro, and Philosophy Bro that don't quite fit anywhere else. Send your questions to philosophybro@gmail.com with 'Mailbag Monday' in the subject line.

Petey Pueblo writes via e-mail:

Oh Wise Philosophy Bro, what's the deal with Occam's Razor?

Bro, good question. Occam's Razor is a principle that says, roughly, that we should prefer the simplest explanation. 


Occam, in addition to being a bro, was a nominalist, which means he didn't believe in universal properties, things like redness or humanness. He was trying to answer a hypothetical question – what the hell is ‘red’? Not a red thing, just… red. Before God made anything at all, was there 'red' just bumming around in the heavens with Him? Did God create 'red' and then start applying it to shit, or did he just create shit that happens to give us a particular sensation of seeing a color?  Occam thought we didn’t need a universal ‘red’ to explain red things. The existence of these universal, abstract properties was useless. They were just a bunch of things floating around where no one could see them doing no work, and we could easily just get rid of them. Sure, properties make sense, but we don’t need them, kind of like that uncle you have that never really does anything but you have to be nice to him at holidays and shit. Generally, he thought, if one explanation tells us as much as another and uses fewer different things to do so, you should prefer it. 


Since then, metaphysicians - the bros who deal generally with ultimate reality - have trended toward sparser and sparser theories of what exists. Aristotle started out with thirteen categories of things when he wrote the Categories, categories like place, relation, qualities, and time;  David Lewis, who passed away in 2001, thought everything could be reduced to concrete objects or sets, for a grand total of 2 categories. Other bros have said “uh, fuck two,” and developed theories where everything is reducible to properties. Occam's Razor in this scenario says that if this theory can explain everything that David Lewis' can, with one fewer category, we should prefer it. That is, of course, the money question for any theory – can it really explain as much as the more complex theory?

There have been several different technical statements of Occam’s Razor, but they all give rise to the same problem: it's hard to decide what exactly is the 'simplest'. For example, given Occam's original interpretation, we should prefer the explanation that gravity is a single force that holds us to the earth, rather than believe there are hundreds of thousands of gnomes who pull us down. Okay, question: should we prefer the explanation that there is one God who coordinates everything, or there are three fundamental forces (gravity, electroweak, strong) that dictate the rhythms of the universe? In addition to a bro and a nominalist, Occam was a monk who believed just that: that God was the simplest explanation for everything. Berkeley also used Occam's Razor when he claimed that there was no material world; he said that only God, minds, and ideas existed, and that’s enough to explain the entire observed universe; matter is for suckers.

Should we prefer fewer things or fewer kinds of things? Going back to David Lewis, 2 kinds of things sounds really sweet until you hear that he believes there are uncountably infinitely many concrete universes that are completely isolated and inaccessible from our where all sorts of crazy bullshit happens – in fact, there’s one for everything that could possibly be. Bro, that’s a lot of things in that one category, and maybe there’s a way to do everything those worlds do with sets or propositions or something else that’s simpler, even if that means adding a new kind.

In the philosophy of science, Occam's Razor is used to build models that explain test results. Remember when bros thought everything revolved around the earth? Sometimes the stars and the other planets did weird shit that didn’t make sense, like moving backward in the sky, so astronomers kept adding explanations until the planets were constantly doing mini-donuts while making their major orbit. Then Copernicus and Brahe came along and said, "But look at how much simpler it is when you say the earth revolves around the sun. We get exactly the same results with neat ellipses; you have Venus doing cartwheels and shit." Occam's Razor says we should prefer the theory that the Earth goes around the sun, since it's a simpler explanation for the exact same phenomena.

When someone invokes Occam's Razor in an argument against you, the best way to defeat the argument is to point out something that their theory doesn't explain. Why don't people like one-category theories of properties? Well, it doesn't do a very good job of explaining questions of identity. Why don't more people like nominalism? Well, it doesn't really make sense with sentences like "I prefer blue to green" - how the hell would a nominalist explain that? He doesn’t even believe blue exists. But that sentence seems to make perfect sense, doesn’t it? There are ways around it, but they’re not pretty.

Occam's Razor is often abused and taken out of context, so be wary. I once heard a bro invoke this explanation to say that aliens built monuments like Stonehenge - "which is easier to believe, that early, primitive men had the tools to build the pyramids, or that there were aliens who helped them along? It’s Occam’s Razor, man." Dude... what? It doesn't matter at all what’s easier to believe - anyone who has taken a physics course can tell you it's easier to believe that things fall just befuckingcause than to learn about gravity and shit, but that doesn't have nearly as much power to explain things, and it doesn’t make sense of our observations.

Finally, it’s important to remember that Occam’s Razor doesn’t say anything about the truth of explanations. Some versions of string theory only work in eleven dimensions. Occam would have said, “What? Get the fuck out of here. Eleven?!” But it might be true. It might actually be true that aliens visited us five thousand years ago, as crazy as that sounds; sometimes the dog really does eat your homework after you accidentally get gravy on it while you were hula-hooping indoors, even if that’s not as simple an explanation as ‘I just didn’t do it.’ Occam’s Razor just serves as a helpful guide to deciding which theory we should prefer until further evidence comes to light.

8 comments:

  1. I believe you are now my most favorite page on all the internets!

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  2. agreed. great work with the blog.

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  3. Keep'm coming. I also enjoy when you add external references to further prove your works.

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  4. What's the difference between things falling just because and things falling because of gravity? What is gravity? Is it more than just a label we use to help us feel like we know why things fall?

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  5. It's also important to question the number of things a theory contains. Just because Occam believed that explaining everything with God was the simpler explanation doesn't make it true. Because explaining things with God means that God must be explained.

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  6. @Exhausted...Yeah, your point is valid, but this works just as much with anything else. So, eventually, unless you are willing to invoke an infinite regress (it's turtles all the way down, bro), that point gives you nothing, since that sword cuts both ways, bro.

    Phil Bro, I would be interested if you could bring up what explanation has to do? When we think of human explanations, they have a purpose, for the most part, or are we using logical explanation?

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