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.

It's as if, for Schopenhauer and perhaps Kant, the mind is there up and running, equipped with its categories and concepts that it then projects or smears, as it were, over what impinges upon it from the outside. This is not the image you find in, for example, Chuang Tzu: minds and nature are inseparably fused in an ever-changing whole of experience that, so to speak, constantly wells up from an indescribable source in a process that Daoists call 'the way' or 'the course'.

In the doctrine of the world and humankind as 'will to power and nothing else', Heidegger identified not an antidote to nihilism, but the completion of it. For what can be more destructive of truth and value than the doctrine that these are simply the impositions on the world of human exercises of power?

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.

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.

Gardening is an excellent example of a practice to which, as Alasdair MacIntyre puts it, certain virtues are 'internal'. Good gardening requires a certain goodness on the part of the gardener: care, humility, patience, and respect, for example.