Via Ed Brayton’s blog last Halloween, we have this story of Raelians attempting to debunk the Roman Catholic doctrine of transubstantiation.

In this study we tested the Catholic dogma of transubstantiation by DNA analysis. Results showed unequivocally that the rituals performed by the priests during the Eucharist sacrament have no detectable effect on the substance of altar bread at the DNA level.

Very amusing, but pointless. The reason the doctrine is called “transubstantiation” instead of “transformation” is because when Catholics say “transubstantiation” they mean something very different from transformation. And it all goes back to Aristotle.

In the Raelian paper, it’s obvious that they are using “substance” as a synonym for “material” or “ingredients,” i.e. the stuff that something is made of. That’s a perfectly valid usage of the word, but that’s not the kind of substance that Catholics have in mind when they speak of transubstantiation.

Transubstantiation is based on Aristotelian philosophy, and in Aristotle’s philosophy, the “substance” of a thing means that essential identity that makes it what it is. Take a chair, for example. Some chairs have 4 legs, some have 3, and some only have one. Chairs come in different sizes, shapes, and colors. There are, perhaps, an infinite variety of chairs, and yet they all share in the same “substance,” the same “chair-ness,” that makes them all chairs.

What about those other attributes of the chair, like its size, shape, color, and so on? Well, those are what Aristotle termed the “accidents”—the qualities possessed by the chair that neither define nor modify the essential chair-ness of the chair. In other words, all chairs share the same essential substance, the same chair-ness, yet the accidents take that essential substance and express it in a wide range of forms such that, in extreme cases, you might not even recognize the result as a chair.

What the doctrine of transubstantiation does is to apply that concept to the substance of the bread and wine, such that the ritual takes away the essential bread-and-wine-ness of communion, and replaces it with body-and-blood-of-Christ-ness, while leaving behind the “accidents” of being made of wheat flour and fermented grape juice. If you take the Raelian study to a decently trained Catholic priest and shout, “See? Science found nothing here but bread and wine!” the priest will likely roll his eyes and say, “Well duh, of course that’s what they found, that’s just the accidents. Consecration does not change the accidents.”

This was Thomas Aquinas’ contribution to transubstantiation: he’s the guy who figured out how to make a plausible(-ish) sounding argument for why communion really is the body and blood of Jesus, when anyone can see that it’s still just bread and wine. By taking this obscure, abstract, somewhat strained technical definition of “substance,” he succeeded in arguing that the change was, in some sense, “real.” Or at the very least, he succeeded in befuddling people to the point that they were willing to just take his word for it. So now they believe that it is really the body and blood of Jesus, even though they themselves can plainly see, and feel, and taste, that it is bread and wine.

Completely nuts? Of course. This is ordinary philosophical mumbo-jumbo and hand-waving designed to trick us into believing some kind of magical change has occurred even though material reality remains the same. It’s an old apologetics trick, based on material stolen from pagan Greek philosophers. And not even correct material at that! Aristotle was a smart guy, but he made a few mistakes, and the doctrine of transubstantiation exploits one of them in order to deceive even otherwise-intelligent believers.

Aristotle’s mistake was in believing that substances exist in and of themselves, when in fact the qualities he categorized as “substance” are really just conceptual short-cuts that our brains use in order to cope with the fact that the world contains more information than the human mind can handle. No two dogs are exactly alike, but if we had to conceptualize each and every dog in the world as something novel and unique, our brains would be full of information about billions of individual dogs, and then we’d have no room left over to consider cats and parakeets.

What we do, then, is group our perceptions into patterns based on shared characteristics. We group together all domestic four-legged barking pets as “dogs”, and then we can conveniently refer to billions of individual instances by using only a single concept. Same thing with chairs: they’re not chairs because some essential substance of “chair-ness” exists independently somewhere out in some abstract, ideal universe. They’re chairs because it’s convenient for us to refer to a very large number of instances using only a single concept. The “chair-ness” is a shortcut that exists only in our own minds.

Consider, for example, what happens when you have an old wooden chair with a large crack down the middle of the seat and joints that are deteriorating badly. Rather than continue sitting on it until it collapses painfully underneath you, you decide to break it up into firewood and throw it in your fireplace. What happens to the substance of the chair?

If you’re Aristotle, you’re going to need to invoke another mystical, magical transubstantiation by which the essential chair-ness of the chair is replaced by an essential firewood-ness, since once you’ve smashed it down into nice kindling-sized bits, ready to burn, it’s essentially firewood. And yet, even while it’s clearly firewood now, you can still look at it and see a broken chair. In this intermediate state, it seems to have both substances, which it cannot do, because an Aristotelian substance defines what a thing is, and not just what it looks like.

This is the problem with transubstantiation: Aristotle was wrong about the “substance” of a thing being an independent existence. It’s not. It’s just something that exists in the mind of the observer, which is why the same thing can contain multiple “substances” depending on how many different ways we’re willing to look at it. When the priest “consecrates the host,” he’s changing the Aristotelian “substance” of the bread and wine, which means only that he’s changing the way believers look at it. The “substance” of the consecrated host is the believers’ perception of it as the true body and true blood of Jesus (which means that, in their own minds at least, they are willingly and intentionally committing cannibalism).

So nice try, Raelians, but you’ve missed your shot. Transubstantiation is wrong, but not because it fails to transform the accidents. That’s expected. The real reason it’s wrong is because it’s a cheap philosophical trick based on a false assumption.