 (Kripke used a similar argument in his 1972/80. For versions of it see Chalmers 1996, 93–171; 2010, 141–205; Levine 2001; Nagel 1974; Stoljar 2001.) Clearly the conceivability argument is valid. However, both its premisses are problematic. They are unclear as stated, and controversial even when clarified. A key question is how we should understand ‘conceivable’ in this context.