 if your cerebrum gets put into my head tomorrow, your current mental states will have their characteristic effects in the being who ends up with that organ, and not in the empty-headed thing left behind. By Shoemaker’s reasoning, the subject of those states—you—must therefore be the being who ends up with your transplanted cerebrum. Any being whose later states or actions are caused in the appropriate way by your current mental states must be you. In other words, psychological continuity of a sort must suffice for you or any other mental being to persist through time. Since no sort of psychological continuity suffices for any organism to persist … it follows that no organism could have mental properties. The nature of mental properties makes it metaphysically impossible for animals to think. (Olson 2007: 33–34.)