I know as certainly as I know anything that I'm conscious. You know the same fact with the same certainty about yourself. The problem of whether I can know tha

I know as certainly as I know anything that I'm conscious. You know the same fact with the same certainty about yourself. The problem of whether I can know that about you is a different problem altogether. Edit: Or to put it another way which might be clearer: If it's possible for you to doubt whether you yourself are conscious then you define "consciousness" differently than I do, and so we are talking past each other.