 A possible response to Boghossian is that full or deep understanding of normative concepts like “wrong” requires understanding that certain paradigm cases are wrong, though a more superficial understanding which can be captured by non-substantive account of wrong does not. An analogy with causation might help. A superficial understanding of why opium causes sleep is that it has dormative powers. But a deeper, more detailed understanding would involve understanding how the chemicals in opium affect the neurons in the brain and how those in turn cause sleep. Problems will remain with the “lack of deep understanding” reply to Boghossian’s argument: how does one explain the fact that professional moral philosophers sometimes have different intuitions about substantive claims about what is wrong? One would expect them to have equally deep understanding of the relevant normative concepts and so to have the same a priori intuitions on the understanding-based account of intuitions that Boghossian argues against. But sometimes they do not, as Boghossian notes (forthcomingb). At the same time, he offers an explanation of why the intuitions of philosophers diverge: the theories they hold can affect the intuitions they have.