The question of whether content externalism poses a threat to the traditional view of self-knowledge has been much debated. Compatibilists have tried to diffuse the threat by appealing to the self-verifying character of reflexive judgments about our own thoughts, while incompatibilists have strenuously objected that this does not suffice. In my paper I argue that this debate is fundamentally misconceived since it is based, on both sides, on the problematic notion of ‘knowledge of content’. What this shows, I argue, is not that content externalism is unobjectionable, but that the real challenge to content externalism is not an epistemological one. The real difficulty concerns the content externalist’s seemingly necessary commitment to the idea that individuals have an incomplete grasp of the concepts that go into their own thoughts. This idea poses a threat not to self-knowledge, I argue, but rather to our first- and second-order reasoning abilities.