Heterosexuality, which I define as a romantic and sexual orientation toward persons not of one's own sex, is apparently a very general, though not entirely universal, characteristic of the human condition. In fact, it is so ubiquitous a part of human interactions and relations as to be almost invisible, and so natural-seeming as to appear unquestionable. Indeed, the 1970 edition of The Shorter Oxford English Dictionary defines ‘heterosexual’ as ‘pertaining to or characterized by the normal relation of the sexes.’

In two passages of A Theory of Justice Rawls suggests that, as a consequence of his egalitarian theory, the natural talents of persons are common property.

Common sense morality contains a concept of openness and accords positive value to behavior that exemplifies it. But it is unclear what morally valuable openness is and what sort of value it has in ordinary moral thinking.

Part of Berkeley's strategy in his attack on materialism in the Three Dialogues Between Hylas and Philonous is to argue that the epistemological distinction between ideas of so-called primary qualities and ideas of secondary qualities, especially as this distinction is found in Locke, is untenable. Both kinds of ideas-those presenting to the mind the quantifiable properties of bodies (shape, size, extension, motion) and those which are just sensations (color, odor, taste, heat)-are equally perceptions in the mind, and there is no reason to believe that one kind (the ideas of primary qualities) represents true properties of independently existing external objects while the other kind does not.

Kant defined ‘sensation’ (Empfindung) as ‘the effect of an object on the representative capacity, so far as we are affected by it.’ This is, to put it mildly, not one among his more elegant, clear or helpful sayings. And it is merely an instance of a more general malaise. Kant did not say as much about sensation as he should have, and his account-or lack of it-can be seen at the root of many of the difficulties that have plagued his readers.

At least since Augustine, philosophers have constructed developmental just-so stories about the origins of certain concepts. In these just-so stories, philosophers tell us how children must develop these concepts. However, philosophers have by and large neglected the empirical data about how children actually do develop their ideas about the world. At best they have used information about children in an anecdotal and unsystematic, though often illuminating, way (see, for example, Matthews, 1980).