Does Symmetry Exist?

Well, duh, yes.

But is symmetry a thing? Well, no. Again, duh.

The reason I bother to bring this up in the first place is that I’ve stumbled on the festering swamp of pretentiousness that is Edward Feser’s blag

One thing that annoys me is the way he constantly reifies ideas, and acts as though that Means Something.

Take a look for instance at this bit (he begins by summarizing a physicist’s post about philosophy):

Arguments for God as cause of the universe rest on the assumption that something can’t come from nothing.  But given the laws of physics, it turns out that something can come from nothing. 

Here was my reaction:

Is this guy serious?  The laws of physics aren’t “nothing.”  Ergo, this isn’t even a prima facie counterexample to the principle that ex nihilo, nihil fit.  That’s just blindingly obvious.  Is this guy serious? 

In other words, what Feser is saying is that a law of physics is something. Is this true?

So let me back up a bit and look at symmetry (for simplicity, I’ll just consider mirror symmetry). Some objects, like cue balls and 2×2 Lego bricks, look the same in a mirror as they do by themselves (plus or minus however much we care about; if we care about the specific positions of atoms, a cue ball isn’t symmetrical; if we don’t care about the number indicating the point value, an “M” tile from a Scrabble set is symmetrical).

This fact can be expressed in multiple ways. In English, it feels natural to say that an object has symmetry. In another language, such as French, one might say “this object is symmetrical”. In yet another language, the most natural way to express this (or indeed the only way) might be to say “this object mirrors-without-changing” or “this object endures mirrorily”.

Whether the idea is expressed using a noun, an adjective, a verb phrase, an adverb, or even as a mathematical equation, it doesn’t change what the object is. People from any country can look at at the object and agree whether it has this particular property.

So what is “symmetry”, then? Presumably it’s some data structure in the mind of an English speaker that gets excited when she thinks of an object that looks like its mirror image. An artifact of the way that person processes information about the world, that happens to be implemented as a noun.

But just because there’s a noun for something, that doesn’t mean that that something actually exists out there in the world.

And a law of physics isn’t a thing. It’s a statement about how things behave. In fact, it can be expressed as an if-then statement: “if certain things existed and certain conditions held, then such-and-such would happen”. For example, the statement “if my refrigerator had a mass of 100 solar masses, it would collapse into a black hole” is true even though my fridge doesn’t mass anywhere near that much, due to the way that implication statements work. So a statement like “all masses attract through gravity” can be expressed as “if there were any masses, they would attract” and would thus be true even if there weren’t any masses in the universe.

But in the end, a law is a statement about how things behave; it isn’t a thing itself. And when people talk about the universe starting from nothing, they’re generally wondering how all this stuff came to be here in the first place.

Now, it’s certainly fair to ask why stuff in the universe behaves the way it does, and whether the laws of physics could have been different, whether there are other worlds where they are different, and so on. But when Feser says “The laws of physics aren’t `nothing'”, he’s projecting the way his mind works onto the universe and trying to make that someone else’s problem. It’s as if he had asked the name of the man in the moon, or asked why two holes don’t repel each other, since they have negative mass.

This strikes me as sloppy thinking (and related to the use-mention error). And I see it all too often when I read Sophisticated Theologians™. Which is one reason why I have as little respect for that occupation as I do.

One thought on “Does Symmetry Exist?”

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