 The traditional versions of neutral monism—those developed by Ernst Mach, William James, and Bertrand Russell (see section  4  below)—accept (1) and reject (2). But some critics of neutral monism, notably Bostock (2012: 190, 195–6), interpret neutral monism as committed to (2). Based on this interpretation of neutrality, Bostock arrives at the striking conclusion that “Russell’s version of neutral monism was never properly ‘neutral’ or ‘monistic’” (Bostock 2012: 190).