Allow me to take the question a little more generally.Are there living beings or are living beings possible without consciousness?
It is an interesting question and the subject certainly extends into many different fields such as neurology, philosophy, psychology, computer science and, in my opinion, physics.I cannot give you a reliable statement, only my personal opinion.
There are different assumptions for consciousness.Some assume that a neural network, which is complex enough, will eventually automatically develop consciousness and it is only a form of emergence in a sufficiently complex system.
Personally, I am a supporter of the (admittedly heavily criticized) Hameroff-Penrose model, which states that consciousness is a quantum physical effect, which is caused by the fact that several neurons form a common wave function. .
In medicine and neurology, there are now various diseases that affect consciousness, such as delirium.There are fluid transitions between subsyndromalem delirium, delirium, coma and death. The states differ greatly from the expression of the still existing consciousness.
In the usual delirium model, arousal (excitation) and attention (attention, but actually this is supposed to reflect consciousness) are assumed.The arousal now only describes the electrical activity in the brain, as well as general signal processing, while the attention describes consciousness. It now seems that in order to gain attention, a minimum activity of Arousal is needed and the two are thus coupled with each other.
If there is now a disease that affects brain activity, consciousness is first affected before the severe and (partially then) visible failures occur.However, the threshold of consciousness is now not evenly distributed throughout the brain, so it is difficult to reach a state in which the entire brain slips slightly below the threshold of consciousness, but at the same time the arousal is still sufficiently high.
For example, there is a disease in neurology called denblindness.Some of these people claim that they can no longer see, but they can still unconsciously react to light signals. It used to be believed that these people were lying, but the truth is that in these people only the part of the brain that is supposed to transfer the visual information into consciousness no longer works. The subconscious signal processing still works, but there is no more consciousness here.
If you could now manage to drive activity in the brain in all areas to just below the threshold of consciousness, then I could well imagine that this person could still “work”, but rather behave like a “robot”.
So the crucial question is what a living being or machine can do with an awareness that is not possible without consciousness.One could now answer the question according to computer science and say that a machine without consciousness corresponds to a normal Turing machine and can execute corresponding programs.
Perhaps it is possible with awareness even more and also non-turing problems to solve.But back to the question. There should probably be no people completely unconscious who are not in a coma or are already dead. But there are many people who have limitations in their quantitative and qualitative awareness, e.g. due to illness.