Even if I could by gradual degrees be transformed into a bat, nothing in my present constitution enables me to imagine what the experiences of such a… - Thomas Nagel

A feature of experience is subjective if it can in principle be understood only from one type of point of view: that of a being like the one having the experience, or at least like it in the relevant modality. The phenomenological qualities of our own experiences are subjective in this way. The physical events in our brains are not. Human physiologists may take a special interest in them; but they can, in principle, be understood just as well, or even better, by creatures totally unlike us in physical and mental structure. To understand them such creatures need not take up our point of view. Physical brain processes can be understood objectively, from the outside, because they are not subjective phenomena. And no description or analysis of the objective nervous system, however complete, will ever by itself imply anything which is not objective, i.e. which can be understood only from one kind of viewpoint, that of the being whose states are being described. One cannot derive a pour soi from an en soi.

There will never be [a general and complete theory of right and wrong], in my view, since the role of judgment in resolving conflicts and applying disparate claims and considerations to real life is indispensable. Two dangers can be avoided if this idea of noncomprehensive systematization is kept in mind. One is the danger of romantic defeatism, which abandons rational theory because it inevitably leaves many problems unsolved. The other is the danger of exclusionary overrationalization, which bars as irrelevant or empty all considerations that cannot be brought within the scope of a general system admitting explicitly defensible conclusions. This yields skewed results by counting only measurable or otherwise precisely describable factors, even when others are in fact relevant. The alternative is to recognize that the legitimate grounds of decision are extremely various and understood to different degrees. This has both theoretical and practical implications.

Usually, when we are told that X is Y we know how it is supposed to be true, but that depends on a conceptual or theoretical background and is not conveyed by the 'is' alone. … But when the two terms of the identification are very disparate it may not be so clear how it could be true … and a theoretical framework may have to be supplied to enable us to understand this. Without the framework, an air of mysticism surrounds the identification.<p>This explains the magical flavor of popular presentations of fundamental scientific discoveries, given out as propositions to which one must subscribe without really understanding them. For example, people are now told at an early age that all matter is really energy. But despite the fact that they know what 'is' means, most of them never form a conception of what makes this claim true, because they lack the theoretical background.