 These arguments lend substantial support to non-psychologism and suggest that being motivated by a reason is not acting in light of, or guided by, a mental state, or by a fact about one’s mental states. Along with other arguments, they have led many philosophers (see Alvarez 2008, 2009b, 2010; Bittner 2001; Dancy 2000, 2008; Hornsby 2007, 2008: Hyman 1999, 2015; McDowell 2013; Raz 1999; Schueler 2003; Stout 1996; Stoutland 1998; Williamson 2000, among others) to reject psychologism. But non-psychologism is not free from difficulties. A central problem for non-psychologism is presented by “error cases”. If motivating reasons are facts, then what is the agent’s reason in cases, like Othello’s, where the agent is in error and is motivated to act by a false consideration? In such a case, what the agent would give as his reason—say, that Desdemona has been unfaithful—is false. So, Othello cannot act in light of the fact that Desdemona has been unfaithful. And non-psychologism does not seem to have a ready answer to what the motivating reason is in these cases.