[W]hen most people think about an immaterial soul that persists after death, they have in mind some sort of blob of spirit energy that takes up residence near our brain, and drives around our body like a soccer mom driving an SUV.
Armed with such a definition as a first principle, Sean makes quick work of the idea of immortality through the standard interaction-problem argument, though I very much liked his way of framing the argument. After giving the Dirac equation for the activity of electrons, he says:
If you believe in an immaterial soul that interacts with our bodies, you need to believe that this equation is not right…. There needs to be a new term (at minimum) on the right, representing how the soul interacts with electrons. (If that term doesn’t exist, electrons will just go on their way as if there weren’t any soul at all, and then what’s the point?)
I’ll have to take Sean’s word for it that the equation has been applied, say, to an electron in some guys big toe and has successfully accounted for everything his foot did during the experiment, or to an electron in some guys mouth and has successfully accounted for what he was saying, but Sean is the physicist, so it’s best to assume he knows about this sort of stuff. But back to the argument. Sean’s clever move is that he’s framed the discussion so that he demands that someone answer as a physicist, but an idea like soul has no value in physics. So why did I bother including the snarky quasi definition that Sean is demolishing? Because it is still closer to the truth than the notion of soul that Carroll is working from.
Talking about an immortal soul requires some consensus on what a soul is at all, and the largest, longest lasting, and most diverse tradition on this point claims that a soul is whatever a living body has that a dead body doesn’t. If the older words for “soul” are any indication (anima, pneuma, spirit), we first claimed that this thing was breath. Living bodies breathe. Dead bodies don’t. Such materialism is so earthy it makes even Carroll seem spiritual. Nevertheless, to call this soul misses the point – while breath is a very good sign of life, it’s doubtful that anyone ever considered the passage of air from one side of your nostrils to another as the reason for of life.
The next simplest account, and the first that really touches on what the soul might be, asserts that the soul is the activity of an organ. We can understand breath not as simply the air that is inhaled and exhaled, but the whole working system that breathes in and out. Here, at least, we’ve moved beyond the level of simply noting a sign of life and have given a bona fide operation of life. That said, all the explanation amounts to is that the life of the person depends on the life of their respiratory organs. Saying I’m alive if my lungs are doesn’t say much.
The first real account we get of what the soul is – which is still firmly materialistic – is that the soul is some arrangement of parts which, of themselves, are not living. The Greeks called this the theory that the soul was a harmony, and it is still the simplest theory of the soul (though we would probably dump “harmony” in favor of something more scienecy- sounding). The theory is continually abandoned for various reasons, the simplest being that arrangement is a feature of position or place, but if all one does is change the position or place of something, it doesn’t cease to be what it is. If all there was to being alive was arrangement, then death wouldn’t change what a thing was – which would mean that a cow doesn’t cease to be a cow when it dies.
To remedy the defect in thinking that the soul is some arrangement of non-living things, it would make sense to introduce a soul that simply lived by nature. Though a body can either live or not, we introduce some thing X which simply lives by nature. On this account, a body lives like water is sweet. Of itself, water isn’t sweet or bitter, but the same can’t be said of a packet of Koolaid mix. In the same way, bodies of themselves aren’t living or non-living, but the same can’t be said of soul. There are materialist versions of this account (where we say that the soul is fire or some material elan vital) but the theory on the whole is repugnant to materialism, since it’s precisely body which we say is neither alive or not. This theory has its own problems too, some of which are similar to what Carroll notices. There are good refutations of the point, and Carroll’s argument might well count as one, but it is still closer to the truth than the arrangement theory.
And there’s the rub. For while Carroll has a point in refuting the sort of substance-dualism that posits different substances as mere quantitative parts (or quasi quantitative parts) of a living thing, his own theory of soul is simply a more primitive arrangement theory. At the heart of his critique is that all there is are clouds of electrons, variously arranged, and dutifully following the Dirac equation. Even if we accept Carroll’s critique (and there is much truth in it), to accept his own position on the matter would still be a regression to a less reflective and less adequate theory. By the logic of his own position, at the next stage we’ll just junk the science altogether and go back to writing poetry about the soul, with shades in the underworld, spirits struggling forth from bodies “when the dark blood ran”…. Hmmm…. Go Sean! Keep it up!