Panpsychism is the philosophical position that consciousness occurs everywhere in the universe — that snails, trees, amoebas, rocks, thermostats, and electrons all, in some sense, have experiences. Clearly, such a philosophical position is of interest to animists and shamanists, even if it is not quite the same position that animists and shamanists hold about the universe.

Panpsychism would seem to be the logical consequence of holding two prior philosophical positions. These positions are, first, psychophysical dualism — that experiences, mental events, or, as they are called now, qualia are all different from and not logically supervenient upon any particular set of physical facts; and, second, non-emergentism — that experiences, mental events, or qualia do not emerge at some particular point in the development of organizational complexity.

The first of these two positions holds that conscious experience is both different from and irreducible to any state, however complex, of any physical stuff. And there certainly appear to be two different kinds of event in the world — physical events, such as changes in the state of a neurological system; and experiences, mental events, or qualia, such as a pain, a sensation of heat, a visualized red patch, or a feeling of anger. It is one thing to say that some, or even all, qualia are invariably associated with certain specifiable physical events; it is another to say that those qualia are the same as, or nothing but, or reducible to those physical events.

It seems to me obvious that, when I close my eyes and picture a patch of red, my experience of red is qualitatively different from any state or activity of the three-pound lump of gray stuff inside my skull. The existence of conscious experience is undeniable; that we are conscious is precisely what we know best. Clearly that intuition is not shared by some philosophers, who seem covertly, for philosophical reasons, to deny the existence of cosncious experience. Frankly, I am sometimes left wondering just what the mental life of those people must be like, and whether it is anything at all like mine. In such a state of befuddlement, I am always reminded of a famous joke. Two behaviorists had just made love. One turns to the other and says, “It was good for you. Was it good for me?”

Moreover, there are a number of vigorously disputed arguments that no conceivable set of physical facts sufficiently explains the fact of conscious experience, and thus that mental events are not logically supervenient upon — are irreducible to — any set of facts about the physical world. Here are three.

Consider the logical possibility of a zombie — that is, a creature physically identical to me, molecule by molecule, but lacking conscious experience entirely. Physiologically and psychologically we perceive the same green grass and blue sky; we give similar accounts of our perceptions; we react similarly to the same call to dinner from the next room. But phenomenologically we are distinct: none of the zombie’s functioning is accompanied by conscious experience. The fact that the existence of such a zombie twin is not logically incoherent demonstrates that consciousness fails to supervene logically on the physical.

Or again: Assume that conscious experiences were different than they are now even though all the physical facts of the universe are the same. Let us say that, whenever sufficient energy from a given portion of the electromagnetic spectrum impinges on my retina, I have a conscious experience of red, and whenever sufficient energy from a different portion of the electromagnetic spectrum impinges on my retina, I have a conscious experience of blue. There is nothing logically inconsistent about picturing a universe in which the color experiences are inverted — where in the first instance I have a blue experience instead of a red one, and in the second instance a red experience instead of a blue one. Again, the fact that it is logically coherent for all the physical facts of the world to remain fixed but the phenomenological facts to differ demonstrates that conscious experience does not supervene on the physical.

Or again: Consider Mary, who lives at a time when neuroscience is complete, when we know everything there is to know about the physical processes in the brain. In a time of triumphant neuroscience, Mary is a leading neuroscientist, specializing in the neurophysiology of color vision. But Mary has been brought up entirely in a black-and-white room, and has never seen any colors other than black, white, and shades of gray. Mary knows everything there is to know about color perception — except that she does not know what it is like to see red. There is no way for Mary to derive the experience of red even from her complete knowledge of the physical facts about red perception. A similar point is made this way. Assume we know everything there is to know about the physical facts of the mouse. We still cannot tell, from those facts alone, whether a mouse has any conscious experiences or not.

There is, in fact, a peculiar epistemic asymmetry about conscious experience. Consciousness is a surprising feature of the universe; even if we knew all the physical facts about the universe, that knowledge would not lead us to postulate the existence of conscious experience. There is, in fact, only one ground for a belief that conscious experience exists — our own individual experience of it. We may be tempted to infer that other beings have conscious experience; but the very intractability of the problem of other minds only reinforces this peculiar asymmetry. There is no similar problem of, say, other lives, precisely because life is logically supervenient on the physical. Only in the case of conscious experience are we asymmetrically dependent on our own experience rather than upon observation and inference regarding the world.

So experience would seem to be simply a brute fact about the world, which cannot be explained in terms of the properties of the complex systems that most obviously exhibit it, and which cannot be reduced to the properties of those systems. And brute features of the universe — such as mass, energy, or charge — just do not suddenly appear only when associated with certain complex physical structures such as the brain. There seems to be nothing about matter that would cause conscious experience to arise from it; there seems to be no way to arrange small bits of unconscious stuff that would result in the consciousness of the larger bits of stuff of which they are the constituents. We can see, more or less, how constituent molecules that are not themselves liquid might be assembled to make larger things that are, just as we can make a baseball team fom nine things that are not baseball teams. But nothing of that sort seems available to explain the emergence of consciousness from wholly nonconscious matter.

If experience is not reducible to a physical substrate, and if it does not emerge at a given level of complexity, it follows that experience must have been already present at the lowest levels of organization. In other words, conscious experience is everywhere — not only in mice and shrimp, but also in trees, amoebas, and, presumably, individual spleen cells.

But mental events, experiences, consciousness everywhere? We can get used to the idea by moving conceptually down the scale of complexity. Humans perform very complex information processing and have correspondingly rich conscious experiences. There can be little question that dogs also have conscious experiences — even that they have meaningful conscious experiences. Mice, too, are conscious in some way, although probably not prone to contemplative introspection; still, there is something it is like to be a mouse, and the perceptual manifold of a mouse may well be relatively rich, with correspondingly rich experiences.

As we move down the scale through lizards and fish to slugs, there does not seem to be a point where consciousness suddenly winks out. Undoubtedly it is less interesting to be a fish than to be a human, with a simpler phenomenology corresponding to a simpler psychology; but there is no reason to believe that there is nothing there at all. So where on this continuum would consciousness wink out altogether? Where would we ascribe such a radical discontinuity?

It is no doubt boring to be a thermostat — perhaps even boring in ways a human might find difficult to understand. But to think of a thermostat as having an extraordinarily primitive set of conscious experiences is simply an extension of the same reasoning we apply to dogs and fish and slugs. There does not seem to be anything obvious that a slug has that a thermostat does not. The fact that it is clear how a thermostat works, or that it is easy to build a thermostat, and that conscious experience is not part of the mechanism or the design, does not differentiate a thermostat significantly from a brain. Conscious experience cannot be located in a brain either.

But even if panpsychism is a viable philosophical position, important questions remain about what this means for an animist or shamanist. For example: does the claim that a tree is, somehow, conscious, or has experiences of some sort, support the different claim that the tree has, or is, a spirit?

What panpsychism does do is to open up a very shamanic sense of awe and wonder at the world, awaken us to the mysterious interpenetration of all beings, give the world a startling dimension of depth. It allows us unselfconsciously to greet the sun, to stroke a tree, to ponder the ineffable intelligence of a gamma ray.