From PhilPapers forum Logic and Philosophy of Logic:

2012-04-07
Is it impossible to suppose the Liar?
Reply to Kris Rhodes
There is reasonable doubt concerning (4). Not only is the individuation of thoughts problematic, but it seems that to suppose X is NOT to entertain a single thought. The fact that (2) is true does not mean/ entail that I entertain a single thought. Nor can I assume that.