What must be true for you to see a yellow station wagon? To begin with, there must actually be a yellow station wagon. If there isn't, you may think – you may even say, quite sincerely – that you see a yellow station wagon, but you are simply wrong. It only looks like a yellow station wagon. Maybe you are hallucinating – or just terribly confused.

Since there obviously are (or were) yellow station wagons I have never seen, what else must be true for me to see one? Once again, most folks will agree that there must be some causal relation between the station wagon and me. It must, somehow, affect me. If the car is in your garage, then I can't see it, because the garage walls prevent a causal interaction. Light reflected from the car never reaches my eyes. If you run the engine, I might hear it (in this case, the causal relation between the car, or the car's engine, and me is via my ears), but I won't see it.

Just affecting me, though, is surely not enough. Many things affect me that I never perceive. I don't have to see or feel poison ivy (the plant) for it to affect me. I know it was there, in the field I walked through yesterday, but not because I saw it. I know it was there because today I perceive the effects – an ugly rash – that it had on me.

Many people think the mind evolved. Some of them think it had to evolve. They think the mind not only has a history, but a history essential to its very existence.

Of those who think it had to evolve, some think it because they discern, or think they discern, a normative quality to mental affairs, a way mental states and activities {qua mental) are supposed to be, that can only be understood by conceiving of mentality as a product of an evolutionary process. Without a process like natural selection (or learning), processes capable of grounding a difference between how things are and how they are supposed to be, there is nothing to provide the requisite contrast with existing fact, the sort of contrast implied by speaking (as we do in cognitive affairs) of beliefs, perceptions, and inferences as correct or incorrect, mistaken or fallacious, right and wrong, veridical and illusory. If this normative quality is really essential to cognitive affairs, and history is the only source of normativity, then history is to minds what it is to fossils. Without the right history, there aren't any.

Since the arguments for this view are not entirely convincing—even to someone like me who accepts their conclusion—and the consequences of the view, I keep being told, are preposterous, I take this occasion to re-examine the matter. If I am to continue believing not just that the mind is a product of historical development, but, like a fossil, can only exist in that way, I need better reasons than I've already got.

Never mind differences that make no difference. There are none. I want to talk, instead, about differences that do not make a difference to anyone, differences of which no one is aware. There are lots of these.

According to Daniel Dennett, though, there are fewer than you might have thought. There are, to be sure, physical differences – even some that exist in you – of which you are not aware. There are also conscious events in me, and differences among them, that you don't know about. But there are no conscious events in you that escape your attention. If you do not believe yourself to be having conscious experience φ, then φ is not a conscious experience at all. Dennett calls this view, a view that denies the possibility in principle of consciousness in the absence of a subject's belief in that consciousness, first-person operationalism. Dennett is a first-person operationalist. For him there are no facts about one's own conscious life – no, as it were, conscious facts – of which one is not conscious.

Philosophers like to call each other names. I'm no exception. The preferred term of abuse these days, especially among materialists, seems to be “Cartesian.” So I will use it. First-person operationalism sounds like warmed-over Cartesianism to me. For Descartes, the mind is an open book. Everything that happens there is known to be happening there by the person in whom it is happening.

The hard problem of consciousness, the place where the explanatory gap is widest – viz., the nature of phenomenal experience – is especially vexing for people who believe that:

1. Conscious perceptual experiences exist inside a person (probably somewhere in the brain)

2. Nothing existing inside a person has (or needs to have) the properties one is aware of in having these experiences.

The experience I have when I see (dream of, hallucinate) a large orange pumpkin has to be inside me. Why else would it cease to exist when I close my eyes, awaken, or sober up? Yet, nothing inside me – certainly nothing in my brain – has the properties I am aware of when I have this experience. There is nothing orange and pumpkin-shaped in my head. How, then, can I be aware of what my perceptual experiences are like – presumably a matter of knowing what qualities they have – if none of the properties I am aware of when I have these experiences are properties of the experience?

Surely, though, we are, in some sense, aware of our own conscious experiences. We have, if not infallible, then privileged, access to their phenomenal character. I may not know what it is like to be a bat, but I certainly know what it is like to be me, and what it is like to be me is primarily – some would say it is exclusively – a matter of the phenomenal qualities of my perceptual (including proprioceptive) experience.

If consciousness is good for something, conscious things must differ in some causally relevant way from unconscious things. If they do not, then, as Davies and Humphreys conclude, too bad for consciousness: “psychological theory need not be concerned with this topic.”

Davies and Humphreys are applying a respectable metaphysical idea – the idea, namely, that if an object's having a property does not make a difference to what that object does, if the object's causal powers are in no way enhanced (or diminished) by its possession of this property, then nothing the object does can be explained by its having that property. A science dedicated to explaining the behavior of such objects would not have to concern itself with that property. That is why being an uncle is of no concern to the psychology (let alone the physics) of uncles. I am an uncle, yes, but my being so does not (causally speaking) enable (or prevent) me to do anything I would not otherwise be able to do. The fact that I am an uncle (to be distinguished, of course, from my believing I am an uncle) does not explain anything I do. From the point of view of understanding human behavior, then, the fact that some humans are uncles is epiphenomenal. If consciousness is like that – if it is like being an uncle – then, for the same reason, psychological theory need not be concerned with it.

Knowing that something is so, unlike being wealthy or reasonable, is not a matter of degree. Two people can both be wealthy, yet one can be wealthier than the other; both be reasonable, yet one be more reasonable than the other. When talking about people, places, and topics (things rather than facts), it makes sense to say that one person knows something better than another. He knows the city better than we do, knows more Russian history than any of his colleagues, but doesn't know his wife as well as do his friends. But factual knowledge, the knowledge that something is so, does not admit of such comparisons. If we both know that today is Friday, it makes no sense to say that you know this better than I. A rich man can become richer by acquiring more money, and a person's belief (that today is Saturday, for example) can be made more reasonable by the accumulation of additional evidence, but if a person already knows that today is Friday, there is nothing he can acquire that will make him know it better. Additional evidence will not promote him to a loftier form of knowledge – although it may make him more certain of something he already knew. You can boil water beyond its boiling point (e.g., at 300° F) but you are not, thereby, boiling it better. You are simply boiling it at a higher temperature.

There is a difference between hearing Clyde play the piano and seeing him play the piano. The difference consists in a difference in the kind of experience caused by Clyde's piano playing. Clyde's performance can also cause a belief – the belief that he is playing the piano. A perceptual belief that he is playing the piano must be distinguished from a perceptual experience of this same event. A person (or an animal, for that matter) can hear or see a piano being played without knowing, believing, or judging that a piano is being played. Conversely, a person (I do not know about animals) can come to believe that Clyde is playing the piano without seeing or hearing him do it – without experiencing the performance for herself.

This distinction between a perceptual experience of x and a perceptual belief about x is, I hope, obvious enough. I will spend some time enlarging upon it, but only for the sake of sorting out relevant interconnections (or lack thereof). My primary interest is not in this distinction but, rather, in what it reveals about the nature of conscious experience and, thus, consciousness itself. For unless one understands the difference between a consciousness of things (Clyde playing the piano) and a consciousness of facts (that he is playing the piano), and the way this difference depends, in turn, on a difference between a concept-free mental state (e.g., an experience) and a concept-charged mental state (e.g., a belief), one will fail to understand how one can have conscious experiences without being aware that one is having them.