 There is neither a single resolute/Pyrrhonian nor a single substantial/non-Pyrrhonian reading of Wittgenstein. Moreover, there is an important difference between the resolute–substantial and Pyrrhonian–non-Pyrrhonian distinctions. The former distinction arises from a continuing debate on how to read Tractatus Logico-Philosophicus, both on its own and in relation to Philosophical Investigations (see, e.g., Conant 2004 and Mulhall 2007), and is associated with the so-called New Wittgensteinians (see, e.g., Crary and Read 2000). The Pyrrhonian and non-Pyrrhonian discussion is to be found, for example, in Fogelin (1994), Sluga (2004), and Stern (2004, 2007), and concerns the ways in which Wittgenstein might be considered as writing in the tradition of the ancient Pyrrhonian sceptics, who were philosophically sceptical about the very possibility of philosophy (see Fogelin 1994, pp. 3ff and 205ff). These distinctions cut across the distinction between Orthodox and Kripkean non-orthodox readings of the text: both Orthodox and Kripkean non-orthodox interpreters have tended to offer substantial or non-Pyrrhonian readings of Wittgenstein—though the line may not always be clear and some (e.g., Hacker, 1990) move from a resolute/Pyrrhonian to a substantial/non-Pyrrhonian reading without remarking the fact.