The dis-incumbenced stance is the one people should cultivate, we are told, once they recognize that there is no world beyond the human world. They will, indeed must, have their beliefs and values, but they will recognize that these 'lean upon' - and are answerable to - nothing other than human commitments and purposes. The only fidelity, Rorty remarked, can be to our own conventions.

Like Nietzsche's own writings on education, most of mine were relatively youthful ones. Both were inspired by a critical animus against prevailing trends in education: in Nietzsche's case, the production either of 'useless', dry-as-dust scholars or people 'useful' for the needs of an expanding industrial economy; in my case, a similar subjection of education to economic imperatives, but also to ideological obsessions, notably with promoting 'equality'.

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.

Chuang Tzu and Heidegger both emphasise the virtue of 'spontaneity' - a sort of mindful responsiveness to things as they are. It's this notion, I suspect, that is the best bet for helping to make some sense of talk about harmony or unity with nature.

I think it's true that for existentialist thinkers, appreciation of what we are - free, makers of meaning, 'issues' for ourselves, and so on - is at the same time a recognition of how we should try to live.

The question of meaning goes all the way down: if human life as a whole is meaningless, so is everything that occurs or belongs within it. Since that's not a thought it is easy to live with, there is good reason to search for life's meaning.

The focus of environmental ethics should indeed be on the virtues and how these inform our relationship to natural environments.