Can you prove a negative? I’ve argued that this is the classical last-ditch defense of God, and, beyond the existence of a deity itself, nowhere is that argument more salient that when comes to the soul and the afterlife. How could we possibly get evidence against a soul, or against its immortal survival in regions above? This question also relates to the frequent claims of accommodationists—employees of the National Center for Science Education come to mind—that you can’t test the supernatural.
Well, you can under one condition: if the supernatural is supposed to leave traces in the material world but doesn’t (rain dances and prayer are two examples). A subset of this occurs when “supernatural” claims posit phenomena that are totally incoherent or nonsensical according to what we know about the universe. (Remember, conclusions about the absence of God and his workings are, like all scientific conclusions, provisional. There is evidence for a deity that I would accept; I just haven’t seen any.)
Over at Cosmic Variance, physicist Sean Carroll claims that we already know enough to dismiss the idea of an immortal soul as a scientific possibility (that is, a thing that has a real existence)—and I agree. His post from Monday, “Physics and the immortality of the soul,” has already stimulated a huge number of comments (I haven’t read them). His argument is simple, and based on physics:
Admittedly, “direct” evidence one way or the other is hard to come by — all we have are a few legends and sketchy claims from unreliable witnesses with near-death experiences, plus a bucketload of wishful thinking. But surely it’s okay to take account of indirect evidence — namely, compatibility of the idea that some form of our individual soul survives death with other things we know about how the world works.
Claims that some form of consciousness persists after our bodies die and decay into their constituent atoms face one huge, insuperable obstacle: the laws of physics underlying everyday life are completely understood, and there’s no way within those laws to allow for the information stored in our brains to persist after we die. If you claim that some form of soul persists beyond death, what particles is that soul made of? What forces are holding it together? How does it interact with ordinary matter?
Everything we know about quantum field theory (QFT) says that there aren’t any sensible answers to these questions. Of course, everything we know about quantum field theory could be wrong. Also, the Moon could be made of green cheese.
Among advocates for life after death, nobody even tries to sit down and do the hard work of explaining how the basic physics of atoms and electrons would have to be altered in order for this to be true. If we tried, the fundamental absurdity of the task would quickly become evident. . .
But let’s say you do that. How is the spirit energy supposed to interact with us? Here is the equation that tells us how electrons behave in the everyday world:
[it’s the Dirac equation.] . . . As far as every experiment ever done is concerned, this equation is the correct description of how electrons behave at everyday energies. It’s not a complete description; we haven’t included the weak nuclear force, or couplings to hypothetical particles like the Higgs boson. But that’s okay, since those are only important at high energies and/or short distances, very far from the regime of relevance to the human brain. If you believe in an immaterial soul that interacts with our bodies, you need to believe that this equation is not right, even at everyday energies. There needs to be a new term (at minimum) on the right, representing how the soul interacts with electrons. . .
. . Nobody ever asks these questions out loud, possibly because of how silly they sound. Once you start asking them, the choice you are faced with becomes clear: either overthrow everything we think we have learned about modern physics, or distrust the stew of religious accounts/unreliable testimony/wishful thinking that makes people believe in the possibility of life after death. It’s not a difficult decision, as scientific theory-choice goes.
Indeed! Those who specify the existence of souls and afterlives in this scientific era must do more than issue fuzzy-minded gobbledygook. They must specify more precisely what they’re talking about, and how it’s supposed to work. If we’re supposed to survive after death, what part of us survives, and how? And what is this soul, exactly? We’re no longer in the Middle Ages, so theologians who make empirical claims must be empirically specific. As Sean notes, there are biological questions as well. The first ones that occurs to me are these: where, exactly, in the human lineage did the soul emerge? (Or do other species have souls?) Was it put into that lineage by God, or did it evolve? If instilled by God, when? And where in our body does it reside? If we retain our memories and personalities in the afterlife, how do they exist without neurons?
Of course theologians will respond to all of the above like this, “We don’t have to tell you what souls are, or in what form you survive after death. We just know it’s true because we just know that there’s a God and that he allows these things.”
The proper answer to that, of course, is Hitchens’s Dictum: “What can be asserted without evidence. . .”
It’s time to make theologians get specific. For too long we’ve let them get away with fuzzy-mindedness.
And Good for Carroll. He’s a nice guy—the kind of guy whom you don’t expect to be be stirring up this hornets’ nest—but he loves truth more than he loves adulation. (There’s no easier way to gain public approbation than by coddling religion.)
There’s a lot more than this in Sean’s post, so go read it.