A theory of consciousness initially proposed by David Chalmers (in his book the Conscious Mind) is that consciousness (or experience) is a property of information processing systems. It is an additional property, not logically implied by physical laws; a new law of nature. The theory was later formalized by Giulio Tononi into Integrated Information Theory, based on Shannon’s mathematical concept of information. One important feature of this theory is it is a radical form of panpsychism: it assigns consciousness (to different degrees) to virtually anything in the world, including a thermostat.

The Bewitched experiment of thought

I have criticized IIT previously on the grounds that it fails to define in a sensible way what makes a conscious subject (eg a subsystem of a conscious entity would be another conscious entity, so for example your brain would produce an infinite number of minds). But here I want to comment specifically on the example of the thermostat. It is an interesting example brought up by Chalmers in his book. The reasoning is as follows: a human brain is conscious; a mouse brain is probably conscious, but with a somewhat lower degree (for example, no self-consciousness). As we go down the scale of information-processing systems, the system might be less and less conscious, but why would it be that there is a definite threshold for consciousness? Why would a billion neurons be conscious but not a million? Why would a million neurons be conscious but not one thousand? And how about just one neuron? How about a thermostat? A thermostat is an elementary information-processing system with just two states, so maybe, Chalmers argue, the thermostat has a very elementary form of experience.

To claim that a thermostat is conscious defies intuition, but I would not follow Searle on insisting that the theory must be wrong because it assigns consciousness to things that we wouldn’t intuitively think are conscious. As I argued in a previous post, to claim that biology tells us that only brains are conscious is to use circular arguments. We don’t know whether anything else than a brain is conscious, and since consciousness is subjective, to decide whether anything is conscious is going to involve some theoretical aspects. Nonetheless, I am skeptical that a thermostat is conscious.

I propose to examine the Bewitched experiment of thought. In the TV series Bewitched, Samantha the housewife twitches her nose and everyone freezes except her. Then she twitches her nose and everyone unfreezes, without noticing that anything happened. For them, time has effectively stopped. The question is: was anyone experiencing anything during that time? To me, it is clear that no one can experience anything if time is frozen. In fact, that whole time has not existed at all for the conscious subject. It follows that a substrate with a fixed state (e.g. hot/cold) cannot experience anything, because time is effectively frozen for that substrate. Experience requires a flow of time, a change in structure through time. I leave it open whether the interaction of the thermostat with the room might produce experience for that coupled system (see below for some further thoughts).

What is “information”?

In my view, the fallacy in the initial reasoning is to put the thermostat and the brain in the same scale. That scale is the set of information-processing systems. But as I have argued before (mostly following Gibson’s arguments), it is misleading to see the brain an information-processing system. The brain can only be seen to transform information of one kind into information of another kind by an external observer, because the very concept of information is something that makes sense to a cognitive/perceptual system. The notion of information used by IIT is Shannon information, a notion from communication theory. This is an extrinsic notion of information: for example, neural activity is informative about objects in the world in the sense that properties of those objects can be inferred from neural activity. But this is totally unhelpful to understand how the brain, which only ever gets to deal with neural signals and not things in the world, sees the world (see this argument in more detail in my paper Is coding a relevant metaphor for the brain?).

Let’s clarify with a concrete case: does the thermostat perceive temperature? The thermostat can be in different states depending on temperature, but from its perspective, there is no temperature. There are changes in state that seems to be unrelated to anything else (there is literally nothing else for the thermostat). One could replace the temperature sensor with some other sensor, or with a random number generator, and there would be literally no functional change in the thermostat itself. Only an external observer can link the thermostat’s state with temperature, so the thermostat cannot possibly be conscious of temperature.

Thus, Shannon’s notion of information is inappropriate to understand consciousness. Instead of extracting information in the sense of communication theory, what the brain might do is build models of sensory (sensorimotor) signals from its subjective perspective, in the same way as scientists make models of the world with observations (=sensory signals) and experiments (=actions). But this intrinsic notion of information, which corresponds eg to laws of physics, is crucially not what Shannon’s notion of information is. And it is also not the kind of information that a thermostat is dealing with.

This inappropriate notion of information leads to what in my view is a rather absurd quantitative scale of consciousness, according to which entities are more or less conscious along a graded scale (phi). Differences in consciousness are qualitative, not quantitative: there is dreaming, being awake, being self-conscious or not, etc. These are not different numbers. This odd analog scale arises because Shannon information is counted in bits. But information in the sense of knowledge (science) is not counted in bits; there are different kinds of knowledge, they have different structure, relations between them etc.

Subjective physics of a thermostat

But let us not throw away Chalmers’ interesting experiment of thought just now. Let us ask, following Chalmers: what does it feel like to be a thermostat? We will examine it not with Shannon’s unhelpful notion of information but with what I called “subjective physics”: the laws that govern sensory signals and their relations to actions, from the perspective of the subject. This will define my world from a functional viewpoint. Let’s say I am a conscious thermostat; a homunculus inside the thermostat. All I can observe is a binary signal. Then there is a binary action that I can make, which for an external observer corresponds to turning on the heat. What kind of world does that make to me? Let’s say I’m a scientist homunculus, what kind of laws about the world can I infer?

If I’m a conventional thermostat, then the action will be automatically triggered when the signal is in a given state (“cold”). After some time, the binary signal will switch and so will the action. So in fact there is an identity between signal and action, which means that all I really observe is just the one binary signal, switching on and off, probably with some kind of periodicity. This is the world I might experience, as a homunculus inside the thermostat (note that to experience the periodicity requires memory, which a normal thermostat doesn’t have). In a way, I’m a “locked-in” thermostat: I can make observations, but I cannot freely act.

Let’s say that I am not locked-in and have a little more free will, so I can decide whether to act (heat) or not. If I can, then my world is a little bit more interesting: my action can trigger a switch of the binary signal, after some latency (again requiring some memory), and then when I stop, the binary signal switches back, after a time that depends on how much time my previous action lasted. So here I have a world that is much more structured, with relatively complex laws which in a way defines the concept of “temperature” from the perspective of the thermostat.

So if a thermostat were conscious, then we have a rough idea of the kind of world it might experience (although not how it feels like), and even in this elementary example, you can’t measure these experiences in bits - let alone the fact that a thermostat is not conscious anyway.