Externalism and skepticism: Recognition, expression, and self-knowledge

As I am sitting at my desk in front of my computer, a thought crosses my mind: There's water in the glass. The thought has a particular content: that there is water in the glass. And, if all is well, there is water in the glass, so my thought is true. According to external-world skepticism, I still do not know that there is water in the glass, because my way of telling what's in front of me does not allow me to rule out the possibility that I’m only under some kind of illusion about what's in front of me. Analogously, according to content skepticism, I cannot know that I am thinking that there is water in my glass, even if in fact that is what I am thinking. This is because for all I know, my way of telling what I am thinking does not allow me to rule out the possibility that I am only under some kind of illusion about what I am thinking.