 Now, none of these approaches is unobjectionable, and it remains to be seen which, if any, is to be preferred. Concern about the Aristotelian approach can relate to whether it can show that belief in X is necessary for intelligible thought in general, or for thought by creatures like us—where if it only establishes the latter, the possibility of a skeptic raising intelligible doubts about it would seem to remain, while establishing the former seems extremely demanding if not impossible (cf. Körner 1967). Further, the worry might be raised in a Stroudian spirit, that all this approach shows is that doubts cannot be expressed concerning X, but where that then seems to fall short of establishing that X is really the case. And finally, while it may perhaps seem right to say that there is something unintelligible or meaningless about questioning the principle of non-contradiction (although this can also be challenged: cf. Priest 1987), other skeptical doubts do not seem problematic to the same degree. (For further discussion points of this sort, see Illies 2003: 54–63.) Along similar lines, critics have also questioned Strawson’s naturalistic approach, as not fully answering the skeptical challenge: for even if a doubt here is ‘idle’, it does not follow that what is questioned is really true (cf. Valberg 1992: 168–96, Sen 1995). Likewise, when it comes to Stroud’s position, as he himself admits, the indispensability and invulnerability he speaks of ‘might not seem like much reassurance in the face of a general scepticism’ (Stroud 1999: 168), given that it not only does not rule out the possibility of falsity, but also seemingly gives no additional reasons for taking that possibility less seriously. Moreover, it has been suggested that Stroud’s position is unstable, as the claim that certain beliefs are invulnerable on the one hand, and the acceptance that they might be untrue on the other, seem to stand in tension with one another (see Brueckner 1996). The position proposed in Stern 2000 tries to get round these difficulties, but has also been accused of ducking important aspects of the skeptic’s challenge (see e.g., Sacks 1999 and 2000: 276–85; and for Sack’s own positive proposals, see Sacks 2005a, 2005b and 2006). Finally, for an attempt to adopt an approach that is neither ambitious or modest, but somewhere between the two, see McDowell 2006.