Brian Loar is credited with devising this strategy. Close attention to the strategy reveals it to be much more obscure than it seems at first sight. Although it pretends to answer the knowledge argument, it actually focuses only on the ‘explanatory gap’ and the ‘conceivability of zombies’’. This enables its protagonists to represent the problem as concerning the relation between two sets of concepts – how one can infer from physical facts to certain mental facts. In fact the problem for the physicalist is to explain how the properties apparently present in qualia can be the same as some ascribed by science to states of the brain. This was the issue that earlier theories, such as Smart’s and Armstrong’s faced up to, but PCS simply tries – unsuccessfully – to evade.