Every night I dream. And often when I dream I seem to think that I am awake. Is it possible, then, that I'm dreaming now, as I sit here, or seem to, in my office?
How should I go about addressing this question? The natural place to start, it seems to me, is with my opinions about dreams -- opinions that might be entirely wrong and ill-founded if I'm dreaming or otherwise radically deceived, but which I seem, anyway, to find myself stuck with.
Based on these opinions, I don't find it at all likely that I'm dreaming. For one thing, I tend to favor a theory of dreams on which dreams don't involve perception-like experiences but rather only imagery experiences (see Ichikawa 2009). If that theory is correct, then from the fact -- I think it's a fact! -- that I'm now having perception-like experiences, it follows that I'm not dreaming.
However, theories of this sort admit of some doubt. In the history of philosophy and psychology, as I seem to recall, many thinkers have held that when we dream we have experiences indistinguishable from waking perceptions -- Descartes held this, for example, and more recently Allan Hobson. It would be foolish arrogance to think there is no chance that they are right about this. So maybe I should I should accept the imagination model of dreaming with only, say, 80% credence? That seems pretty close to the confidence level that I do in fact have, when I reflect on the matter.
But even if I allow some possibility that dream experiences are typically much like waking perceptions, I might remain confident that I'm not dreaming. After all, I don't feel like I'm asleep. Maybe my current visual, auditory, and tactile sensory experiences could come to me in a dream, but I think I'm more rational in my cognition than I normally am when dreaming. And I recall, seemingly, a more coherent past. And maybe the stability of the details of my experience is greater.
But again, it seems unwarranted to hold with 100% confidence that dreams can't be rational, coherent, and stable in the way my current attitudes and experience seems to be. After all, people (if I recall correctly) have pretty poor knowledge of the basic facts about dream experience (for example, its coloration). Or even if I do insist on perfect confidence in the instability, incoherence, and irrationality of typical dreams, it seems unwarranted for me to be 100% confident that this is not an exceptional dream of some sort. So maybe I should do another 80-20 split? Or 90-10? Let's say the latter. Conditionally upon a 20% credence in a theory of dreams on which we have waking-like sensory experiences while dreaming, I have about 90% confidence that, nonetheless, my current experience has some other feature, like stability or rational coherence, that establishes that I am not dreaming. That would leave me about 98% confident that I am awake.
But I can do better than that! On some philosophical theories, I couldn't even form the opinion that I might be dreaming unless I really am awake. Alternatively, maybe it's just constitutive of being a rational agent that I assume with 100% confidence that I am awake. Or maybe there's some other excellent refutation of dream doubt -- a refutation I can't currently articulate, but which nonetheless justifies my and others' normal assumption, when awake, that they are indeed awake. Such theories are attractive, since no one (well, almost no one) wants to be a dream skeptic! Dream skepticism is pretty bizarre! So hopefully philosophy can succor common sense in this matter, even I don't currently see exactly how. I'm not extremely confident about any such theory, especially without any compelling argument immediately to hand, but it seems likely that something can be worked out.
Thus, I am almost certain that I am awake. Probably dreams don't involve sense experiences of the sort I am having now; or even if they do, probably something else about my current experience establishes that I am not dreaming; or even if nothing in my current experience establishes that I am not dreaming, probably there is some excellent philosophical argument that would justify confidence in the fact that I am not currently dreaming. But of none of these things am I perfectly confident. My degree of certainty in the proposition that I am now awake is somewhat less than 100%. I hesitate to put a precise number on it, and yet it seems better to attach an approximate number than to keep to ordinary English terms that might be variously interpreted. To have only 90% credence that I am awake seems far more doubt than than is reasonable; I assume you'll agree. On the other hand, 99.9999% credence that I am awake seems considerably too high, once I really think about the matter. Somewhere on the order of 99.9% (or 99.99%?) confidence that I am currently awake, then?
Is that too strange -- not to be exactly spot-on 100% confident that I am awake?