Alfred North Whitehead’s The Concept of Nature begins with a critique of what he calls “the bifurcation of nature”. Philosophy typically, perhaps unavoidably, divides nature into two realms: one “the Conjecture”, the other “the Dream”.
The Dream is the realm of lived experience. It is made up of what Hume called “impressions” as opposed to ideas — the products of what Descartes called “sensation” and “imagination” as opposed to intellection. It is what, in some sense, we feel and experience rather than what we think, theorise, or posit.
The Dream consists of percepts: sensations, raw feels, items of direct lived experience. It includes shapes, colours, sounds, and smells — pains and pleasures, pangs of love and itches. The sort of reality belonging to percepts does not distinguish between waking experience and experience in dreams. An itch or a colour-image in a dream has no intrinsic distinguishing features from an itch or a colour-image in waking experience. Otherwise, as Descartes argued, we could tell whether we were dreaming or awake by merely attending to the sort of experience we were having.
What makes the difference is theory. Here we come to the Conjecture. The Conjecture consists of the objects of our concepts: theoretical posits that we make to explain our raw experiences, as W.V.O. Quine defined physical objects. This includes the physical objects we posit as the sources of our ‘veridical’ percepts and the brain-states invoked to explain our ‘non-veridical’ percepts — dreams, hallucinations, etc.
Pre-scientific theory tells us that there is an object, the sun, which causes my feeling of warmth and plays a role in causing the various colours and shapes I see. Scientific theory tells us what that object is: a big nuclear reaction far away. The posits of those theories make up the second realm of nature: the Conjecture.
All of our words stand for items in the Conjecture, not in the Dream. Right now I can say I am experiencing a percept of Arthur’s Seat looming between my back garden and a blue winter sky. But Arthur’s Seat, my back garden, and the winter sky all belong to the Conjecture, not to the Dream. I can describe my experience using other concepts, e.g. “a dark green mound against a blue background over a green rectangular patch”. Here “mound” and “background” are still, at least in their clearest senses, terms for physical objects of a sort, and “against” and “over” involve geometrical constructions that belong to the Conjecture. The Dream itself has no dimensions; we do not directly experience some coordinate grid or system of spatial relations among our percepts. Some Post-Kantian philosophers of the mid-twentieth century tied themselves up in knots trying to devise schemes of ‘inner’ or ‘subjective’ space.
There is no Dream-language in which I could describe the scene before me; “scene” is itself a term for an arrangement of physical objects, derived from a word standing for a type of physical object. There is no way to describe the Dream without borrowing the language of the Conjecture. If I describe a percept as, e.g., the feeling of smelling ammonia, I have referred to a type of physical substance that belongs to the Conjecture. If I say “this feeling” gesticulating wildly, I haven’t succeeded in identified anything except perhaps by contextual cues, and when we analyse the contextual cues we will find them full of implicit references to items of the Conjecture.
This point was seized upon by early analytic philosophers in their efforts to refute the Idealist theory that only the Dream is real. At worst they showed that there is no such theory to refute, since each item in the Dream, and thus the Dream as a whole, cannot be referred to at all. Or, to put it in a less self-refuting way, the statement “only the Dream is real” is meaningless, since it contains an empty name.
This disposed of a certain sort of Idealism, though not a sort endorsed by any of the prominent Idealist philosophers, whom the early analytic philosophers felt no obligation to try to understand. But did it prove too much? If the argument is successful, then not only can we not meaningfully say that the Dream is the sole reality; we cannot say it is real at all (nor even that it is unreal). Objects in the Conjecture were invoked in the first place to explain our percepts. But now we can’t even say that there are any percepts. Perhaps they do exist, but we just can’t refer to them? But if so, we cannot meaningfully say so. Analytic philosophy conjectured the Dream away. And without the Dream it is difficult to see the point of the Conjecture.
There was, in something like the third generation of analytic philosophy, a spate of efforts to permit reference to the the Dream by analysing it without residue into items of the Conjecture. For instance, the feeling of watching a sunset, by way of a materialist theory of mind, is fully reduced to some state of the brain. To talk about the feeling is to talk about a physical state of a physical object. Some philosophers wanted to leave bit of residue in the reduction, for instance with the theory that the feeling and the brain-state are the same but identified under different concepts. But then what are concepts? Are they too analysed into items of the Conjecture?
At any rate, these theories did not preserve the Dream as something distinct from the Conjecture. This, to me, is just another way of conjecturing the Dream away.
True Idealism — the kind propounded by the actual Idealist philosophers rather than contrived as a straw man by the early analytical philosophers — might have its revenge in the future. The true Idealist philosophers did not begin by boldly asserting that only the Dream is real. They began, as anyone communicating her thoughts in language must, in the realm of the Conjecture. But they aimed to show that the whole Conjecture collapses under the weight of its own internal contradictions. F.H. Bradley’s famous regress is one attempt to do this; far more impressive in my view are J.M.E. McTaggart’s deconstructions of the concepts of time, space, and matter.
If the Conjecture cannot logically sustain itself then things cannot be as it conjectures, and we are left with only the Dream as our guide to how things are. We cannot then say how things are, but we can feel it, and that is the lesson of philosophy. Whitehead, inspired by Bradley, came to the view that any acceptable philosophical picture of reality must involve a transcendence beyond human language.
I believe that there is something in the Idealist tradition that remains for analytical philosophers to reckon with. If, having conjectured the Dream away, the Conjecture goes on to undermine itself, then surely something has gone wrong. If your philosophy conjectures away everything then it becomes trivially true that there is more in Heaven and Earth, Horatio…