Couldn't "empirical evidence" include that of which we are aware, during consciousness? Is there a major problem in holding that we are aware of our "minds", or at least of our 'awareness', which is a mental state or property? And once you've admitted empirical evidence for the existence of your own mind, are there *serious* objections to granting the existence of others? Alternatively, can't we have empirical evidence that is not of the 'direct observation' variety? I see footprints in the sand and I infer that a person recently walked by, because a person walking by would be the best explanation of what i directly observe. Why not allow that 'other people having minds' might be the best explanation for what we do observe, namely the way others behave and speak etc.?

best, ap

Or stones. They may be quietly thinking of Vienna. (Sorry; irresistible inside joke.)

People who think the mind is material don't think there's some special kind of matter ("Mindium?") that has the power to think. They think that matter appropriately structured and in appropriate relationship with the environment allows organisms to have beliefs, feelings, etc. And "appropriately structured" is best illustrated by things like human brains. The matter in trees and lumps of coal doesn't have anything like the kind of structure that brains do. And so the reasons we have for thinking that purely physical things can have minds don't give us reason to think that just any old physical thing can think.

A footnote: some people have suggested that there's a sort of primitive mental character associated with all matter. The view is called panpsychism. But even panpsychists would generally agree that complex mental processes depend on the right kinds of complex arrangements of matter.

Daniel Dennett discussed a fictional drug that he called an "amnestic" that allows you to feel pain, but paralyzes you so that you don't exhibit pain behavior, and leaves you with amnesia. Pleasant, no? For the details and his philosophical analysis, read:

Dennett, Daniel C. (1978), "Why You Can't Make a Computer that Feels Pain", Synthese 38(3) (July): 415-456; reprinted in his Brainstorms: Philosophical Essays on Mind and Psychology (Montgomery, VT: Bradford Books (now Cambridge, MA: MIT Press), 1978): 190-229.

You have some philosophy questions in here and some psychology questions. The philosophical questions are about (1) whether a machine could ever replicate all human behavior (i.e., pass a "complete Turing Test"), and (2) whether such complete replication of behavior would entail that the machine actually had the mental states that accompany such behavior in humans (i.e., whether a machine's (or an alien!) passing such a complete Turing Test means that it is conscious, self-aware, intelligent, free, etc.). There's a ton to be said here, but my own view is that the answers you suggest are the right ones--namely, that there is no in principle reason that a machine (such as an incredibly complex computer in an incredibly complex robot) could not replicate all human behavior, and that if it did, we would have just as good reason to believe that the machine had a mind (is conscious, intelligent, etc.) as we do to believe other humans have minds. I think there may be severe practical limitations to building such machines, but I think that dualists and John Searle are mistaken to think such functional replication would not require real duplication of the mental properties we have.

So, that brings us to the psychological questions: why do lots of people have so much trouble agreeing with the positive answers you and I are inclined to give to the two questions above? I think you touch on one of the reasons: people's religious beliefs lead them to think that God must give you a soul to give you a conscious mind, free will, etc. Turing himself wondered why an all-powerful God would be limited in his ability to give souls to non-humans or machines. Another reason is that the machines we actually interact with do not yet come close to replicating human behavior. So, it's easy to think that mechanisms simply can't do what we do. Indeed, it's hard for us to imagine that our mechanistic brains could explain consciousness, free will, etc., in part because we have no theory to explain it and in part because we have no models for how mental properties can be composed of material properties.

However, having said all that, I actually think our psychology is such that we are happy to ascribe mental states to metal things. Witness C3PO and R2D2, not to mention all the robots from sci-fi films that look and act like humans. I think that most people can easily imagine machines that behave just like humans, because they do imagine it when they watch these movies (read these stories, etc.). And given our 'theory of mind' system which works to automatically ascribe mental states to other people, animals, etc. that act in certain ways, I think we would have a very hard time not ascribing conscious beliefs, desires, intentions, and intelligence to a robot that looked human and acted human. We might try to hold onto a theoretical conviction that the robot isn't really conscious or intelligent, but that conviction would be betrayed by actual experiences and interactions with the robot. Next time you watch Star Wars, AI, Bladerunner, I Robot, etc. (or even 2001 or Moon where the computers just talk and don't act), try as hard as you can to experience the machines as completely dark on the inside, as completely lacking any thoughts or emotions or intelligence. It's not easy to do. So, my answer to the psychological question is that people only think they believe that machines could never have minds because they have a philosophical or religious theory that tells them to think that, but they won't really think that once they experience such machines in action.

My colleague and I disagree somewhat here, though perhaps on everything essential to your question, we agree.

We all agree that in principle the right kind of "machine" could be every bit as conscious, free, etc.as you and I. And Prof. Nahmias may well be right when he says that if a robot of the C3PO sort acted enough like us, we'd have a very hard time not thinking of it as conscious. I even agree with my co-panelist that people's religious beliefs and the relatively crude character of our actual gadgets may be part of the reason why many people don't think a machine could be conscious.

So where's the residual disagreement? It's on a point that may not be essential, given the way you pose your question. Prof. Nahmias thinks that replicating the functional character of the mind would give us reason enough to think the resulting thing was conscious. I'm not inclined to agree. But that has nothing to do with belief in souls (I don't believe in them and don't even think I have any serious idea what they're supposed to be) nor with the fact that the computers we have are primitive compared to full-fledged people. Interestingly, Prof. Nahmias himself actually identifies -- and agrees with -- the sticking point for folks like me. As he puts it, "we have no theory to explain [how our brains could produce consciousness] and in part because we have no models for how mental properties can be composed of material properties."

Now I don't take this to show that matter appropriately arranged can't be conscious. In fact, I believe that we are just such matter. That is, I agree with folk who think that somehow, I know not how, the right physical goings on make for consciousness. But I don't think a purely functional story will do. And it's not just because I don't know how it would work, but because it seems clear to me that a functional story alone doesn't have the resources.

All this is to say that I take what's often called the "explanatory gap" very seriously. I stay in the materialist cam because there's enough we don't know about matter that I'm cheerfully willing to believe that if we knew more, we might have an explanation for consciousness. As a fall-back, I'm quite willing to go along with Colin McGinn's "Mysterianism": it's matter doing its thing that makes us conscious, but we aren't wired to understand how. But it seems clear to me that not only do we not understand how a purely functional story could fill the gap; we understand enough to know that it couldn't.

On this point I'm cheerfully willing to agree to disagree with Prof. Nahmias; I hope he's willing to do likewise. My point isn't to convince you that he's mistaken, but rather to note that for at least some claims about how matter and mind are related, there are reasons for doubt of a different sort than the ones Prof. Nahmias highlights, though reasons that his own further remarks point to.

Hm, if you haven't *really* experienced it, then how do you know that what you dreamt was accurate? Moreover, even if you haven't had such a kiss exactly, isn't it possible that the specific sensory components of the kiss ARE all things you've experienced, if not exactly in that combination? (Why couldn't the mind rearrange sensory components to creat new overall arrangements -- as it does when we use our imaginations, say?) Most importantly, your question presumes we could never dream about something we haven't experienced while awake -- but why believe that, esp. when this very dream might well refute it? (No doubt your sensory organs have the capacity to detect far more tastes and smells and feels etc. than they ever in fact meet with during waking life; why can't the brain fire, during dreaming, so as to reflect those preivously unactivated capacities?)

best, ap