Hanson's basic contention is that the next big technological leap that will change the face of the world economy will be the ability to create a working copy of a human by "porting" that person's brain into a computer. He argues that this could come much sooner than the ability to create an "artificial intelligence" from scratch, because it doesn't require knowing how intelligence works -- you simply create an emulation program on a really powerful computer, and then do a scan of the brain which picks up the current state of every part of it and how those parts interact. (There's a wikipedia article on the concept, called "whole brain emulation" here.) Hanson thinks this would create an effectively unlimited supply of what are, functionally, human beings, though they may look like computer programs or robots, and that this would fundamentally change the economy by creating an effectively infinite supply of labor.
Let's leave all that aside for a moment, because what fascinates me here is something which Roberts, a practicing Jew, homed in on right away: Why should we believe that the sum and total of what you can physically scan in the brain is all there is to know about a person? Why shouldn't we think that there's something else to the "mind" than just the parts of the brain and their current state? Couldn't there be some kind of will which is not materially detectable and is what is causing the brain to act the way it is?
(Or to use the cyber-punk terminology which seems more appropriate with this topic: How do we know there's not a ghost in the machine?)
Hanson's answer is as follows (this section starts around minute 32 of the podcast):
"I have a physics background, and by the time that you're done with physics that should be well knocked into you, that, you know, certainly most top scientists, if you ask them a survey question will say, 'Yeah, that's it.' There really isn't room for much else. Sorry. It's not like it's an open question here. Physics has a pretty complete picture of what's in the world around us. We've probed every nook and cranny, and we only ever keep finding the same damn stuff.
We have enormous progress on seeing the stuff our world is made of. Almost everything around you is the same atoms, the same protons, electrons, the rare neutrino that flies around. And that's pretty much it. You have to get pretty far off to see some of the strange materials and things that physicists sometimes probe. Physicists have to make these enormous machines and create these very alien environments in order to find new stuff to study because they've so well studied the material around us. The things our world is made out of are really, really well established. How it combines together in interesting ways gets complicated and then we don't get it, but the stuff that it's made out of, we get.
Your head is made out of chemicals. We've never seen anything else. It's always theoretically possible that when something's really complicated and you don't know how to predict the complexity from the parts, you could say, 'Well therefore, it could be this whole is different from the parts, because it's too difficult to predict.'
We should separate two very different issues here. One is technological understanding and knowing how things work and how to make things, and the other is knowing what the world is made of. So, I make this very strong and confident claim: We know what the world is made of, and we know what pieces they are and how they interact at a fine grain. But at higher levels of organization, we don't know how to make other things like, even, photosynthesis in cells. We don't know how to make a photosynthesis machine. You could take your cell phone out of your pocket and take it apart and you wouldn't know how to make a phone like that.... We don't know how it works, but we're pretty sure what it's made out of."
Now, this line of thinking seems fairly familiar to me from talking with materialist/atheists of a scientific bent: We have all these great scientific tools, and all they've ever detected is matter and energy, never a "will" or a "beautiful" or a "soul", and so therefore it's pretty clear that when we talk about our minds we're really talking about our brains and there just isn't anything there except chemicals and electricity.
However, it seems to me that this presents a rather obvious blind spot. We, as human persons, experience all sorts of things which would seem to be evidence of having a will which decides things in a non-deterministic fashion. We also respond to ideas such as "beautiful" or "justice" or "good" in ways that would suggest that there is something there that we're talking about.
When we say, "Physicists have done all this work, and all they've ever found is matter and energy," you are really saying, "Given the tools and methodology physicists use, all they are able to detect is matter and energy." But I'm not clear how getting from that to, "Therefore there is nothing other than matter and energy," is anything other than an assumption.
Is there any valid reason why we should accept the jump from, "Tools that scientists use to detect things can only detect the existence of material things," to "Only material things exist"?
This seems particularly troublesome given that the project here is supposedly to create an emulation program which can be given a brain scan and then act like an independent human. If our experience of being human is that there is something in the driver seat, something which decides what is beautiful or what is right or who to marry or whether we want rice pudding for lunch today, then unless there is some active, non-deterministic thing within the brain which can be measured by this scan, then what you get is going to be, for lack of a better word, dead.