According to Chalmers, this is for three key reasons. First, the philosophical zombie makes one wonder about consciousness’ evolutionary function – how and why did it arise if a zombie could survive and reproduce without it? Second, the zombie raises doubts about physical explanations of consciousness. If any account of physical processes would apply equally well to a zombie, can it really explain the existence of consciousness? Third, and most controversial, it can be used to question materialism, the notion that all things, including consciousness, are results of matter interactions. The zombie implies that consciousness is a quality outside the physical realm.

“The general point is that the logical possibility of zombies is one way of illustrating that there is no logical entailment from physical facts to facts about consciousness, whereas there is such an entailment in most other domains,” Chalmers wrote.