We normally assume that consciousness is knowing what happens in our minds right at the present time. In the next few sections, I'll argue that consciousness does not concern the present, but the past: it has to do with how we think about the records of our recent thoughts. But how can thinking about thoughts be possible at all?
There's something queer about describing consciousness: whatever people mean to say, they just can't seem to make it clear. It's not like feeling confused or ignorant. Instead, we feel we know what's going on but can't describe it properly. How could anything seem so close, yet always keep beyond our reach?
There is a simple sense in which thinking about a thought is not so different from thinking about an ordinary thing. We know that certain agencies must learn to recognize — and even name — the feel of touching a hand or an ear. Similarly, there must be other agencies that learn to recognize events inside the brain — for example, the activities of the agencies that manage memories. And those, I claim, are the bases of the awarenesses we recognize as consciousness.
There is nothing peculiar about the idea of sensing events inside the brain. Agents are agents — and it is as easy for an agent to be wired to detect a brain-caused brain-event, as to detect a world-caused brain-event. Indeed, only a small minority of our agents are connected directly to sensors in the outer world, like those that send signals from the eye or skin; most of the agents in the brain detect events inside the brain. But here we're especially concerned with agents that are engaged in using and changing our most recent memories. These lie at the roots of consciousness.
Why, for example, do we become less conscious of some things when we become more conscious of others? Surely this is because some resource is approaching some limitation — and I'll argue that it is our limited capacity to keep good records of our recent thoughts. Why, for example, do thoughts so often seem to flow in serial streams? It is because whenever we run out of room, the records of our recent thoughts must then displace those of our older ones. And why are we so unaware of how we get our new ideas? Because whenever we solve hard problems, our short-term memories become so involved with doing that that they have neither time nor space for keeping detailed records of what they themselves have done.
What happens when we try to think about our most recent thoughts? We examine our recent memories. But these were already involved in what we were thinking about — and any self-inspecting probe is prone to change just what it's looking at. Then the system is likely to break down. It is hard enough to describe something with a stable shape; it is even harder to describe something that changes its shape before our eyes; and it is virtually impossible to speak of the shapes of things that change into something else each time we try to think of them. And that's what happens when we try to think about our present thoughts — since each such thought must change our mental state! Would any process not become confused that alters what it's looking at? In such a fix, how could one ever hope to be articulate?