In Being No One, Thomas Metzinger attempts to develop a thorough and systematic approach to consciousness and subjectivity – one based fundamentally on a teleofunctionalist and naturalist view of consciousness. In other words, an approach to consciousness that presents it as necessarily supervening on a neural basis and as subject-to and a product-of evolutionary pressures. Perhaps surprisingly, in many ways Metzinger’s project comes across as a neurological updating of Kant’s project. Instead of the ‘conditions’ of possible experience, Metzinger deduces the ‘constraints’ constitutive of phenomenal consciousness and self-consciousness. Unlike Kant, however, Metzinger refuses to describe consciousness in a single, unitary way. With the advances in psychology, neuroscience and phenomenology, we can now achieve a much more detailed and nuanced view of consciousness. One of the most significant aspects of Metzinger’s work is therefore the integration of deficient forms of phenomenal consciousness – ones where a particular constraint may be absent as the result of neurological damage. The end result is a set of necessary and contingent constraints for consciousness to occur. The addition or subtraction of a particular constraint leads to entirely different forms of consciousness.