Consciousness As The Only Reality
The belief that only consciousness is real (really real) is deeply ingrained in philosophy, both western and other. To many people it has seemed as if something like this must be true—that there is no coherent alternative. Consciousness undoubtedly exists, and it is all that exists. The doctrine is usually called idealism, though that label is not…ideal: it is not a form of idealism in the sense of a moral vision, and it is not the view that only ideas exist—that is too restrictive. But it is hard to find an alternative label, so I will stick with this one, with the stipulation that “idealism” means “the doctrine that only consciousness is real”. My question is what the source of this doctrine is: why is it found attractive, even inescapable?
Evidently we need to be clear what is meant by “real” and “reality”. The word is used in many ways (“real estate”, “real time”, “real number”, “real leather”, “keeping it real”), but the philosopher has something metaphysical in mind, captured by the OED definition: “relating to something as it is, not merely as it may be described or distinguished”. For “reality” the entry is: “existence that is absolute or objective and not subject to human decisions or conventions”. The dictionary is contrasting the real with something else, located in the human subject—that which is merely described or distinguished, or that which is a matter of decision or convention. Reality is what does not depend on such human acts or attitudes. The real may thus be contrasted primarily with the fictional—that which is invented or postulated or imagined. Philosophers sometimes speak of “logical fictions” intending these to contrast with real entities. So the doctrine of idealism can be understood as the doctrine that everything except consciousness is fictional or imaginary or postulated: consciousness is real and anything non-conscious is unreal. So it is not that everything is consciousness (fictional things are not)—just that everything real is consciousness. 
The doctrine, then, is that every real thing is an instance of consciousness, though there may be unreal things that are not—fictional things. We could imagine or postulate things that are not instances of consciousness, but they would not be real. Idealism is the view that all actual things are instances of consciousness. So it is intentionally more restrictive than the view that everything we can think about is an instance of consciousness; the quantifier is more limited. Among all the things we can think about or refer to some are real, and these are all cases of consciousness; but there may be other things that are unreal and are not cases of consciousness. This point is important because there are certain things about which the idealist (of one stripe) is not inclined to claim consciousness—things she will agree not to be instances of consciousness. For instance, the entire physical world: that world may be regarded as non-conscious but unreal.  That is, the physical world (the world as described by physics) is a postulated world, a world we imagine or hypothesize; it is not a real world existing independently of all human construction and description. There is such a world—we can talk about it—but it is not real (like the fictional world). Thus the idealist distinguishes between what is real (consciousness) and what is unreal (the physical world): the former is not imaginary or postulated, while the latter is. Alternatively: we create the physical world, as a theoretical construction, but we don’t create the world of consciousness.
Why does the idealist think that the physical world is unreal? One possible answer is that we cannot knowthe physical world: we can only know the world of consciousness, not any world that lies beyond it. Any such world is a matter of inference and uncertainty, not knowledge. The physical world is subject to skepticism. But this is a bad answer: why should the contents of reality be limited by what we can know? Physical objects might be real enough but unknowable (we might all be dreaming but there is a real physical world). Surely the deep roots of idealism don’t depend on skepticism. A better line of thought is this: nothing except consciousness is conceivable. More exactly, we may be able to refer to the physical world, but we can’t conceive of it (compare Kant’s noumena). We can’t form a conception of the physical world comparable with our conception of consciousness. When we try to conceive of that world we come up with nothing but a bare mathematical skeleton devoid of substantial content—while in the case of consciousness we get the actual thing before our mind.  We postulate a world that we cannot conceive—not really conceive. Don’t reply that we can surely conceive of tables and chairs, cats and cities: the idealist will insist that we can only conceive of such things as they are presented to consciousness. What we can’t do is conceive of things independently of how they might appear to consciousness. When we conceive of a brown table, say, we are conceiving of consciousness, because we are conceiving of the appearance of the table toconsciousness; we are not conceiving of what lies behind all conscious experience. We cannot conceive of that as we normally conceive of a table; we need a new mode of conception, such as physics purports to provide (the “absolute conception”).
Now I am not aiming to defend idealism; I am merely trying to diagnose its undeniable attraction. My own view is that the physical non-conscious world does exist, is real, can be referred to, and is completely mind-independent; but I agree that there is a question about its conceivability. It is not conceivable in the intrinsic revealing way that consciousness is conceivable. I thus believe in an inherently inconceivable (except abstractly) physical reality. But I can see how someone might jib at that, insisting that everything real must be conceivable. It is then a short step to idealism. I picture the idealist straining to form a conception of the world as it exists independently of how it appears to consciousness, coming up short, and then concluding that there is no such (real) world. Any such putative world must be at best fictional and unreal, though describable. The idealist equates reality with conceivability (not an absurd equation) and concludes that only consciousness is real. That may be wrong, but it is not merely eccentric. Idealism is an eminently intelligible position with perennial appeal. Consciousness is the only reality because it is the only thing we can really get our minds around; anything else is at best imaginary or a “logical fiction”. The so-called physical world is just an airy abstraction devoid of positive content. Everything except consciousness is elusive, wispy, insubstantial, skeletal, schematic, formal, and colorless. The “absolute conception” of the physical world is scarcely a conception at all, more of a sketch of we-know-not-what, a shadowy simulacrum. By contrast, consciousness is present, full-blooded, throbbing with life, pregnant, substantial, concrete, and shot through with color. It seems real: there is no way it could be imaginary or fictional or just a useful way to organize our thoughts. Nothing else is like that, so nothing else is real–really real. Anything else is either not real at all or not as real as consciousness.  Idealism is the expression of these powerful undercurrents of thought, which is why it has been around for so long. It is not just an outmoded curiosity from a bygone age.
 There are different types of idealism as there are different types of materialism: some types deny the existence of such ordinary objects as tables and chairs (“eliminative idealism”) while others claim to provide an analysis of what such objects consist in (“reductive idealism”). Berkeley’s idealism is an instance of the latter, but I want to make room for the former more radical position too. What unites the two is the thesis that the only real things are instances of consciousness.
 I won’t go into the reasons for maintaining this: see Eddington, Russell, and others on why physics is purely mathematical and structural. Their basic point is that the intrinsic objective nature of matter is not disclosed to our epistemic faculties, so that we can grasp only extrinsic relational aspects of matter, mathematically described. Our conception of matter is like the blind man’s conception of color—remote and sketchy.
 Nothing is as real to us as consciousness, so consciousness is naturally taken to be the sine qua non of reality. In a sense we don’t even have to conceive of consciousness to be struck by its reality—it just hits us between the eyes—whereas our thought about the external world of physics is a willed conceptual construction. Idealism says that what is real to us is what is real tout court, viz. consciousness. Nothing is more real to consciousness than consciousness itself.