What do we mean by words like sentience, consciousness, or self-awareness? They all seem to refer to the sense of feeling one's mind at work — but beyond that, it is hard to say whether there are any differences in what they mean. For instance, suppose that you had just smiled, and someone asked if you had been conscious of this. It would scarcely matter how that question was posed:
Did you just smile? Do you realize that you just smiled? Do you remember smiling? Were you conscious of doing so? Were you aware of it?
Each of these questions really asks what you can say about your recent mental past. In order for you to reply truthfully, Yes, I know I smiled, your speaking-agencies must use some records about the recent activity of certain agents. But what about all the other activities involved in everything you say and do? If you were truly self-aware, wouldn't you know all those other things as well? There is a common myth that what we view as consciousness is measurelessly deep and powerful — yet actually, we scarcely know a thing about what happens in the great computers of our brains. How can we think, not knowing what it is to think? How can we get such good ideas, yet not be able to say what ideas are or how they're made?
Why is it so hard to talk about our present state of mind? We've already seen several reasons for this. one is that the time-delays between the different parts of a mind mean that the concept of a present state is not psychologically sound. Another reason is that each attempt to reflect upon our mental state will change that state, and this means that trying to know our state is like photographing something that is moving too fast: such pictures will always be blurred. In any case, we aren't much concerned in the first place with learning how to describe our mental states; instead, we're more engaged with practical things, like making plans and carrying them out.
How much genuine self-insight is possible for us? I'm sure our memory-machinery provides some useful clues, if only we could learn to interpret them. But it is unlikely that any part of the mind can ever obtain complete descriptions of what happens in the other parts, because, it seems, our memory-control systems have too little temporary memory even to represent their own activities in much detail.