The aim of dis-incumbence is a hubristic one, for it requires confidence in the ability of men and women to live in the belief that nothing they do can, in the end, be justified by anything. That's a belief that it is easy to proclaim in seminar rooms or pubs, but not one that people could actually live with.

To recognize that you are radically free, in Sartre's sense, but then to live as if you weren't, is to live in bad faith, in denial of what you know to be true. And that's not something anyone can sensibly want to do.

I'm very sceptical about the prospects for 'big' environmental causes - 'saving the planet', halving the world's population, ending the exploitation of animals, and so on - but a person can ask him- or herself how he or she personally may exercise compassion or humility towards animals, vegetal life and so on.

I rather shared Nietzsche's conception of the kind of individual that an ideal education should be cultivating. 'Authenticity' is not Nietzsche's term, but as used by some existentialists, it nicely captures what Nietzsche admired - the resolve of an individual person to forge his or her own 'table of values', to be emancipated from strait-jacketing conventions, traditions, and ideologies. As embodied in the 'Overman', authenticity is the antidote to 'bad' nihilism.

Nietzsche's 'perspectivalism' was expressly directed against the 'laughable juxtaposition of "man and world"'. But 'absolutist' accounts, too, typically try to demonstrate that human beings are integral components of the world these accounts articulate - that, for example, we are simply material bodies subject to the same natural processes as everything else.

An abiding and central concern of philosophy and religion alike is the fear that the world is alien to human beings, that nature is, in Hegel's words, 'out and out other' to 'spirit'. It's easy enough to see how 'constructivist' or 'humanist' conceptions are efforts to dispel this fear.

Like Nietzsche, Heidegger also gave up on the prospect that schools and universities would nurture the kind of reflective openness to the way of things that, certainly by the 1940s, he identified with authentic thinking. The authentic person is not the Promethean, iron-willed figure that pops up in Nietzsche, but someone more like the Daoist sages whom Heidegger admired.