The grain argument is meant to cut off reductive replies to these questions.  Sellars’s commentators have often taken it to be a very complex and obscure argument, but Sellars seems to think it is fairly straightforward.  The grain argument works only against attempts to reduce sensory phenomena to more basic atomistic/mechanistic entities.  If the world does not have an ultimate ‘grain,’ then the argument won’t apply. The notion of a reduction must also be specified, for it is notoriously multivalent.  Sellars’s notion of reduction is fairly straightforward: