Either if N is a supermanifold, then there is a space ΠT*N of the cotangent bundle with reversed parity and it has a natural structure of a P-manifold, or it is not the case that if N is a supermanifold, then there is a space ΠT*N of the cotangent bundle with reversed polarity and it has a natural structure of a P-manifold.[note 1] I just asserted a proposition which I don't believe. Indeed, I don't even grasp this proposition. But, nonetheless, the proposition is surely true, because it is a tautology. (I suppose there is the possibility that the sentence doesn't make sense. There, I take it on Alexandrov's authority[note 2] that it makes sense.) I did not violate any duties of sincerity in asserting the sense.
Hence, sincerity in assertion does not require belief.
If s is the first sentence of this post, I can correctly say: "s but I do not believe that s." And so some Moorean sentences are unproblematic.