Various philosophies of mind seem to leave open the possibility of beings that have a physical constitution and brain just like those of human beings, and which behave in identical ways, yet which are not conscious as they do so. Such unconscious replicas of ourselves would be zombies (although unconscious these philosophical creations are not the robotic or ghastly living dead of popular imagination: their behaviour and appearance is exactly that of living people). It is often regarded as a fatal flaw in a philosophy of mind such as Cartesian dualism, or epiphenomenalism, that it not only opens up the possibility of zombies, but leaves one little or no reason to suppose that other people are not zombies, or even that one was not oneself a zombie yesterday, since on these philosophies there is no particular reason to suppose that apparent memories of conscious experience are reliable. See also other minds, analogy.