Ken begins the discussion with the question: what is the difference between being conscious and unconscious? Sense perception is certainly a conscious way in which we relate to the world, but thought tends to occur unconsciously. John carries the point further. The “mind” with all its functioning in thinking and deliberation seems to be a different kind of thing from consciousness. It is not as if there is a subjective state occurring when I deliberate. It is not as if there is something that it's like to deliberate or produce a thought that I am aware of. But if someone steps on my hand, I feel pain. There is something that it's like to be in pain, and I have certainly been aware of the experience. Providing a less violent example: there is something that it's like to eat a chocolate chip cookie. Furthermore, I can tell the difference between being in pain and eating the cookie. The second is pleasurable; the first is not.

This all seems reasonable when applied to me and my experience of my own thoughts, deliberations, and perceptions. But, as Ken aptly points out, it's problematic when we try to claim consciousness for people other than ourselves. John gives this example. I might know that I feel pain when I get stepped on and feel good when I eat chocolate. However, what bearing does that have on you? Perhaps, for all I know, you have the sensation of eating chocolate when I step on your hand and when you eat a cookie perhaps you feel pain and wince.  The real question, Ken explains, is whether anyone from their first person perspective can know anything about someone else's consciousness. Science can explain how the brain works, but it can't account for the way you feel. If we treat other people as if they are conscious, we could be making a misguided assumption.

David Chalmers is the director of the Center for Consciousness Studies at the University of Arizona and has written a book entitled The Conscious Mind. As John puts it, anyone who has done so much work must believe that other people are conscious. But, how would John ever know what's really going on inside Chalmers' head? This is the problem of other minds : I have first-hand knowledge of my own mind, but have no way of accessing the minds of others or knowing whether or not they even have minds. Chalmers takes the first-person subjective experience to be the starting point for determining who has consciousness. I can observe my own awareness. Next, you, a different person from me, verify you are conscious through the same first-person investigation that I used to verify consciousness for myself. The hard part is the third step: I can only assume that you're conscious—I cannot know with certainty that you are. When we make the assumption that other people are conscious, we do so on indirect evidence. We have many things in common as human beings. Our brains and evolutionary histories are remarkably the same. The differences between the DNA patterns of individuals are miniscule. With so much in common, why not have consciousness in common as well? 

• Roving Philosophical Report (Seek To 00:04:25): Amy Standen interviews Dr. Stewart Hameroff, the associate director of the Center for Consciousness Studies at the University of Arizona.

• Sixty-Second Philosopher (Seek To 00:36:50): Ian gives the run-down on everybody's favorite dualist, René Descartes.

• Conundrum (Seek To 00:48:15): Chuck, calling in from Portland Oregon, poses the following puzzle: what kind of attitude should I have toward good things created by bad people? For example, he explains, he enjoys listening to Wagner but is disturbed by the fact that Wagner was an anti-Semite.