Last week I had a twitter argument with Barry Smith about panpsychism and this week I had a twitter argument with Massimo Pigliucci about panpsychism. A similar issue came up in both, so I thought I’d write a post about it. Actually, it concerns an objection that is often raised against panpsychism, which goes as follows:
(A) We don’t have any evidence that consciousness exists outside of brains.
We need to be careful about how exactly we’re understanding this statement, and what exactly it’s being taken to show. Let us initially interpret it to mean:
(B) We have never observed consciousness outside of living brains.
This is certainly true, and you might think at first that this gives us strong reason to doubt panpsychism. But appreciating the following might make you think again:
(C) We have never observed consciousness inside a living brain.
The simple reason for both (B) and (C) is that consciousness is unobservable. You can’t look inside an electron to see if it has experiences, but neither can you look inside a brain and see a person’s feelings and experiences. We know about consciousness not because of any observation or experiment, but because each of us is immediately aware of her or his own experiences.
The following slogan is often thrown around
(D) Absence of evidence is not evidence of absence.
Is (D) anything more than a slogan? The truth is that sometimes (D) is true and sometimes it’s false. It counts as evidence against a theory if the theory implies that we should expect to find a certain entity in certain circumstances, and it turns out we don’t (this fits with a Bayesian way of thinking about evidence). If a theory tells us that we would expect to find a certain particle in certain experimental circumstances, and we run the experiment and don’t find the particle, this gives us grounds for doubting the theory.
Returning to the case of panpsychism, (B) would be evidence against panpsychism only if panpsychism implies that we should expect to observe consciousness outside of brains. But this is clearly not the case. Consciousness is unobservable, and hence, whether or not panpsychism is true, we’re not going to be able to see consciousness in rocks or particles or anything else. It follows that (B) does not constitute evidence against panpsychism.
One might concede that (B) doesn’t give us reason to doubt panpsychism, but nonetheless take it to show that we don’t have any reason to accept panpsychism. The following principle might be offered in support of this:
(E) We should believe in the existence of something only if we can observe it, or if its existence is supported by what we can observe.
I accept that if (E) is true, then we shouldn’t believe panpsychism. But if (E) is true, we shouldn’t believe in consciousness either. As we noted above, consciousness cannot be observed either in or out of brains. If we rigidly follow (E), we will have no cause to postulate consciousness at all. Much simpler to believe that humans are just complicated mechanisms. Daniel Dennett is one of the few who is admirably consistent on this point.
The problem with Dennett’s position is that (E) is false. Despite being unobservable, consciousness is something we know to exist. Our principle should really be not (E) but:
(F) We should only believe in the existence of something only if its existence is supported by observation, or if its existence is better known than what is known on the basis of observation.
As Descartes appreciated over 300 years ago, the existence of our consciousness is known with greater certainty than anything else. The reality of consciousness is a datum in its own right, over and above the data of observation and experiment.
Observational evidence is crucial, but it’s not the full story. If we’re working with observational evidence alone we would have no reason to believe panpsychism, but only because we’d have no reason to believe in consciousness. The case for panpsychism is built not on the basis that it provides a good explanation of observational data, but on the basis that it provides the best explanation of how observational data and consciousness data fit together in a single, unified worldview. A large part of that case involves arguing that rival accounts of materialism and dualism face serious problems (some empirical, some conceptual) that panpsychism avoids. I have not made that case in this blog post. But I hope to have shown that merely pointing out that panpsychism is not supported by observational evidence alone is not to the point. Nobody would claim otherwise.