Last Saturday I penned a snarky comment about the philosophy of science, and within a week I read something that’s particularly interesting from that very perspective. Well, might as well use it when it has its uses. Some preliminary:
It is certainly either true or false that Julius Caesar’s paternal grandfather sneezed on his tenth birthday. Can we figure out which using science? Let’s review what has to be available in order to do science. While there’s always debate at the margins as to what constitutes science, virtually any working scientist will tell you that the main issue is being able to test your hypothesis by observation. Sometimes this is cast specifically as as falsifiablilty; but we have no need to be so picky. Can we test whether the sneeze happened? No, unless science invents a time machine. The sneeze either happened or it didn’t, but we’re in the dark about it and will remain so.
PZ Myers, as is his wont, recently wrote here that after his death he will have ceased to be. In other words, his experience of consciousness will have ended forever. Can we test this?
He could die and then make the observation as to whether or not he still existed. If he still did he’d be surprised, but at least he’d be able to observe that he was still somehow existing. If he didn’t still exist, he’s not around to make the observation of his nonexistence. So personal experimentation can’t verify his prediction. Neither can anyone else’s, for the same reasons. A dead person can’t observe his nonexistence, and a dead person couldn’t communicate their continued existence either on account of being dead.
We live in the world of modern science however, and we have snazzier methods than that. How about the neural correlates of consciousness? An awake person has different brain activity than a sleeping person. Modern neuroscience can in some cases be quite fine-grained about the connection between mental states and neural activity – famously one guy had a single neuron which fired when he thought about the Simpsons. Neural activity is clearly kaput upon death, so is that adequate to say consciousness does not survive death? Could be, a lot of scientists think so.
It’s still not testable though, strictly speaking. Simulate a brain on a computer. Is it conscious? How about if you simulate it on an abacus? How about if you have a huge printed “choose your own adventure” book of neural states, it is conscious? Beats me. But they are exactly analogous to the real squishy brain in terms of their states and processing, and we totally lack a way of saying whether they have conscious experience or not, regardless of how finely we can experimentally examine them. There’s just no way to make that link between computation and qualia. For that matter, there’s controversy on whether conscious experience even exists as anything more than an illusion of brain processes. Daniel Dennett doesn’t think so. I tend to think that hypothesis is self-defeating, but then I have precisely no experimental test for that supposition either. And all that is just trying to test whether conscious experience necessarily is generated by a particular class of physical processes. The other direction is worse – imagine trying to experimentally test whether something without those processes is conscious – for instance, the whole universe in some pantheistic religions, or an immaterial soul in the monotheistic and other religions. But on the other hand lack of testability doesn’t mean it’s impossible; the sneeze certainly isn’t.
Where am I going with this? Nowhere, that’s the point. Clean experimental testability is why I like physics.