Kagan got back to me. The questions I sent are in bold, followed by Kagan's reponses in plaintext.
1. What is your favorite color?
Alas! I do not have a favorite color.
2. What are the strongest arguments against the existence of a soul? Does general anesthetic prove that there is no soul and show that consciousness is solely dependent on the functioning of the brain?
Let's suppose that to believe in a soul is to believe that there is something nonphysical about us, something that is distinct from our physical bodies, something that thinks and decides, and feels and so on. The central argument against believing in the existence of a soul, I think, is that there is no compelling argument for believing in a soul! That is, the burden of proof, I think, falls in this case on someone who thinks that we should believe in such a thing. We don't normally go around positing things without good reason, so is there a good reason to believe in a soul? If not, then we should tentatively conclude there is no such thing. To be sure, there could be an argument for souls. It would be a different matter, for example, if we needed to posit a soul to explain something that we all agree needs explaining. (This is like positing atoms which we cannot see, so as to explain chemical reactions, and so on, which we can see.) And there are arguments that have been offered along these lines by various people. But I think the proposals are not convincing (we can explain the phenomena in question as well, or better, in strictly physical terms). And in the absence of good reason to posit the soul, we shouldn't do so. (This is the same sort of thing as saying that while there could be Martians, we have no good reason to believe in them, so shouldn't posit them until we have compelling reason to do so.)
Some think that explaining consciousness requires positing a soul. And I suppose I would agree that physicalists (who think we are merely physical beings) don't yet have an adequate account of consciousness (the fact that our mental life has a subjective qualitiave aspect, e.g., the ability to feel pain). But it isn't as though soul theorists have an alternative account either! Merely saying, "souls explain consciousness" isn't really offering any kind of explanation. So I don't think consciousness gives us a convincing reason to posit souls.
At the same time, I don't think that things like the fact that anesthetic can cause us to lose consciousness give us reason to deny the existence of a soul either! Dualists (people who posit nonphysical souls as well as physical bodies) have almost always been "interactionists," holding that the body and the soul interact with each other and can cause changes in the other. Thus, for example, they think that my soul can cause my body to do things (like type these words), and that my body can cause my soul to experience things (like seeing the tree outside my window). So the fact that anesthetic can cause the person to fall asleep won't trouble most dualists. They always thought there could be interactions of body and soul like this.
3. Do you believe that the p-zombie thought experiment has any plausibility to it? If so, then what separates a zombie from a non-zombie is metaphysical, since both have the same bodily equipment that, to our knowledge, enables consciousness, yet one lacks a "true first person perspective" anyway. If you and I are beings who exist on a metaphysical plane, then how is this distinguishable from having a soul?
I am guessing by a "p-zombie" you have in mind something that looks and acts just like us, but has no mental life, in the sense that it has no "consciousness"--feels no pain, doesn't experience the color blue, and so on. Most discussions of this sort of creature assume that they have beliefs and desires, just that it doesn't feel like anything "on the inside" to BE such a creature. (Why the name "p-zombie"? I am guessing this is meant to be short for what sometimes gets called a philosophical zombie, to distinguish it from the kinds of zombies shown in horror movies!) Can we imagine such things? Well, it sure seems so. (Although things immediately get tricky, because we aren't always imagining what we think we are imagining. So are we REALLY imagining such zombies, or just thinking we are?) I take it that we can do something that we think is imagining a body that behaves just like our bodies do (speaks, acts, etc.) but has no inner conscious mental life . That is, it feels no pain, and so on, though it behaves like us: it avoids flames and sharp objects, it knows that such things are dangerous and harmful, and it and will SAY that they are painful, and so on. If this is indeed what you mean by a p-zombie, then I think we can imagine such things existing (in some possible world or the other). The harder question is what follows from this mere conceptual possibility, the apparent ability of our mind to imagine such creatures, to conclusions about what is actually logically possible, and what is metaphysically possible, and what is physically possible, and so on. David Chalmers, who most famously argued on the basis of such thought experiments, thinks that we can derive all sorts of surprising conclusions from the intelligibility of such cases. I disagree, though getting into the details is beyond the scope of a short answer like this.
Of course, I do think the following: since I think WE are conscious, I take it that anything that has the VERY same physical components as we do, living in a world with the same laws of physics (and chemistry, and biology, and so on) as we do, WILL be conscious. But for my money, I don't see how this shows anything about the existence of a soul. (Neither did Chalmers.) It just shows that in a world where the laws of nature are the same as the ones in our world, physical things like us will be conscious. But I don't see any argument for a soul here. This might just be a fact about what physical things of a certain sort are like in a world with laws of nature like ours.
4. Do you believe that it is possible for there to be a universal set of ethics, a right and wrong without god existing, and if so, what would do you think it might look like?
I do think it possible for there to be a universal set of ethical rules, objectively true, valid for everyone, and so on, even if there is no God. I argued for this in a conversation I had once with William Lane Craig (who claimed that morality requires God), which can be found online at: https://www.youtube.com/watch?v=Rm2wShHJ2iA I suppose this is another case where I would put the burden of proof on someone else. In particular, on someone (like Craig) who thought that we need God to have morality. I can't see why we should believe this. After all, one can have a reason to move one's hand from a hot stove, even if there is no God to make that true, right? But then, why can't we also have a reason to help someone ELSE move THEIR hand from a hot stove, even if there is no God? Obviously, a quick remark like this can't show very much, so someone who wants to hear me spell out the idea a bit more fully can check out the discussion I had with William Lane Craig. But my own view is that morality does NOT require the existence of God.
Of course, beyond this, there are any number of other worries one might have about the very possibility of an objective morality. I actually don't think the worry about God being required for morality (so what if there is no god?) is the most pressing. I discuss a number of other such worries in a book I published last fall, called Answering Moral Skepticism. One might wonder about what moral facts would look like, and how they could fit into a scientific world view, and whether belief in evolution gives us reason to be skeptical about our moral intuitions, and doesn't the extent of moral disagreement give us reason to be skeptical, and so on, and so forth. It took a book to state and respond to those worries, so sadly I don't have the time to try to lay out these arguments here.
As to what specific moral views I believe in, broadly speaking I accept what gets called a "consequentialist" morality, according to which the morally right act is a matter of bringing about the best possible outcome you can --roughly speaking, making people as happy as possible, and avoiding hurting them (counting everyone equally, indeed counting animals too). Of course there are a lot of details that need to get worked out, but that's the basic idea. However, I hope it is clear that one can accept quite different moral views from this consequentialist one, while still agreeing with me that morality doesn't require the existence of God. One could, for example, be a "deontologist" --thinking that some acts are wrong even though the results are good overall--that other features of actions are morally relevant besides the consequences of those actions--and still think that morality doesn't require the existence of God.