Despite what you might have heard, this is not quite what panpsychists believe
A few weeks ago, Aeon published a short piece by Philip Goff laying out what he calls the simplicity argument for panpsychism. According to panpsychism, consciousness is a fundamental natural property that is ubiquitous in nature. On this view, the complex consciousness of creatures like human beings is explained by reference to the simple consciousness of fundamental physical entities (usually — but not necessarily — very small things like electrons, quarks or strings). Panpsychism thus stands in contrast to most kinds of physicalism, according to which complex consciousness is to be explained by reference to (if not reduced to) the kinds of properties that fundamental physics is concerned with, and to substance dualism, according to which complex consciousness is explained by reference to properties of an entirely nonphysical (and in some cases non-natural) substance.
As I understand it, Goff’s simplicity argument for panpsychism is roughly as follows. Physics is concerned with the behaviour of physical things, but beyond this, it provides no insight into what physical things really are — it is silent regarding the intrinsic (non-behavioural) nature of the physical. But we’re not completely ignorant about the intrinsic nature of the physical, because we know from direct experience that some matter (healthy human brains) possesses consciousness. Consciousness must be an intrinsic property of the physical object that is the brain, because it is not necessary to invoke consciousness to explain the physics of the brain. So knowledge of our own consciousness gives us the knowledge that consciousness is an intrinsic property of some physical things. If we deny that consciousness is an intrinsic property of all (fundamental) physical things, we have to posit some unknown non-conscious intrinsic property. But all things being equal, we ought to prefer simpler theories over more complicated ones. There is no explanatory advantage to positing two kinds of intrinsic properties for the physical, one of them conscious and directly accessible and the other one non-conscious and totally mysterious. If all fundamental physical things have the same conscious intrinsic nature, physics will have the same content as if some things have a conscious intrinsic nature and other things have a non-conscious intrinsic nature. Considerations of simplicity therefore dictate that we suppose all matter has the same intrinsic nature, which involves consciousness.
I’m mostly on board with panpsychism (especially the cosmopsychist variety which I described in this post) but I’m not so sure about this argument. My main worry is that simplicity is a virtue of scientific theories by methodological stipulation. There’s an infinite number of theories that can account for the data; selecting the simplest theory with equivalent explanatory and predictive power narrows down the alternatives and yields theories that are easier to learn, use, test, etc. That’s a good enough reason to apply the simplicity criterion to scientific theories. But I’m not sure that the simplicity criterion yields (or is more likely to yield) true theories, and philosophy of mind aims for truth, not utility. So I’m not sure it’s appropriate to treat considerations of simplicity as dispositive in the context of philosophy of mind the way we would in the context of scientific theorizing.
For further reading, see Goff’s response to some critics of his article: https://conscienceandconsciousness.com/2017/03/18/the-simplicity-argument-for-panpsychism-2/