Consciousness in a Petri Dish
Noe asks us to consider if cells in a petri dish could be conscious like us. But, argues Noe, it is not enough just to think of there being some isolated cells in a dish that are conscious. The cells need energy and generate waste products that must be flushed away. Moreover, we need a complicated stimulation mechanism that substitutes for how they are stimulated in our environmentally situated body.
Noe goes on to consider the requirements for a brain in a vat. This is how Noe puts it:
The vat would have to be very complicated and specialized in order to control the administration of stimulation to the brain comparable to that normally provided to a brain by its environmentally situated body. If you actually try to think through the details of this thought experiment—this is something scientists and philosophers struck by the brain-in-a-vat idea almost never do—it’s clear that the vat would have to be, in effect, something like a living
body. (№ё 2009, pp. 12-13)
But it is irrelevant whether the brain stimulation is complicated or even practically impossible, and it doesn’t follow that we really need a body to be conscious. The logical point is this: given that a brain behaved as usual, without a body, would consciousness remain? If the thought experiment depends on technology that doesn’t exist, it doesn’t matter. We can think of the vat as magical or controlled by Descartes’s evil demon. Thought experiments are the stock-in-trade in the philosophy of mind, and few are realistic, since they usually make logical points. For example, Noe himself admires Putnam’s Twin Earth argument for content externalism. As we saw, in this thought experiment, Putnam imagines a Twin Earth that is type identical to ours, except that the chemical formula for water is XYZ instead of H2O. Why doesn’t Noe object to this thought experiment? Putnam has not proven that there is a world just like ours but where they have XYZ instead of water. I think Noe realizes that Putnam makes a logical point and that Putnam’s argument does not depend on an existing Twin Earth. The same is true with the brain in a vat: it is a thought experiment with a logical point. It is as irrelevant whether we could implement a brain in a vat or not as whether Putnam’s Twin Earth exists or not. Nevertheless, Noe rejects the possibility that human consciousness is something that could happen in the brain or that there could be a brain in a vat as absurd, and offers instead an account of consciousness as achieved through interaction with the world.
This is a relational systems picture, similar to that of the mental capacities of a bacterium we examined earlier; mind and consciousness are achieved through interaction between a living organism and its environment. Consciousness is a property not of an isolated organism, physical structure, or process, but of a dynamic system the organism forms with its environment.11  When Noe raises the question of whether cells in a petri dish could be conscious, he does it to demonstrate how absurd it is to think consciousness could be understood entirely in terms of neural structures or processes. He scales up his thought experiment from isolated petri dish cells to the brain while trying to preserve the sense of absurdity. This is the negative thesis of Noe—that consciousness doesn’t happen in an isolated neural or artificial system decoupled from the body (or a larger organism) and the world.
-  Noe states his position clearly: “My own view is that the suggestion that cells in a dish could beconscious or that you could have a conscious brain in a vat—is absurd; it’s time to overhaul ourstarting assumptions about what consciousness is if they lead us to such a conclusion” (№зё 2009,p. 12).
-  It is illuminating to go back to early work of Francisco Varela to understand the core ideas ofHurley and №зё when they discuss the importance of viewing mind and consciousness in terms ofenvironmentally embedded systems. They are influenced by Francisco Varela’s view of organismsas machines embedded in larger machines. This is how Varela (1979, p. 12) puts it in his Principles