Simon Critchley today in the New York Times series "The Stone"—
Philosophy, among other things, is that living activity of critical reflection in a specific context, by which human beings strive to analyze the world in which they find themselves, and to question what passes for common sense or public opinion— what Socrates called doxa— in the particular society in which they live. Philosophy cuts a diagonal through doxa. It does this by raising the most questions of a universal form: “What is X?”
Actually, that's two diagonals. See Kulturkampf at the Times and Geometry of the I Ching .