In philosophy of the mind, a “zombie” (philosophical zombie or p-zombie) designates a being physically and externally indistinguishable from a conscious being, by its behavior as by its physical constitution, but which, however, does not has no consciousness, no feelings or subjective or personal experiences. Although he behaves as if he were experiencing emotions or sensations, the zombie experiences none, even though the biological and physical processes that determine his behavior are those of a person who experiences them. George Stout, in 1921, was the first philosopher to refer to it in his description of a world that would later be called a “zombie world”: an imaginary world where the physical processes are identical to ours in such a way that human beings behave and act exactly the same way as in reality, except that in this world, human beings are not conscious beings and feel absolutely nothing. However, it was only in the 1970s, in the context of a debate on the validity of physicalism, that this notion emerged following an expression used by the philosopher Keith Campbell – “Imitation man” – to describe a man whose brain states are exactly like ours in physico-chemical properties, but who, unlike real humans, feels no pain or sees any color.
It is to David Chalmers that we owe the development of the “zombie argument”. This argument is advanced by him to show the inadequacy of explanations in terms of physical processes when they relate to the subjective aspects of consciousness. This is a modal argument based on what is conceivable or logically possible: a world of humans physically indistinguishable from ours but where consciousness does not exist is conceivable and therefore logically possible. There is no contradiction to the scenario that there is a universe physically similar to ours in all respects, although the creatures within it are totally devoid of consciousness. David Chalmers regards such a scenario as a pure thought experiment from which one cannot draw a decisive argument. But the logical possibility of the zombie shows that the facts relating to consciousness do not logically reduce to physical facts as we conceive them and that they could well be fundamentally different phenomena. And since we know we are conscious, then we must recognize that our world contains more than physical entities of the type that have mass or electrical charge for example: it also includes non-physical consciousness, or physical consciousness, but understood in a different sense than that given by the current physical sciences.
(Includes texts from Wikipedia translated and adapted by Nicolae Sfetcu)