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.

The Overman will himself be a nihilist in the (good) sense of rejecting any metaphysical or religious grounding for truth and value, but instead of curling up in despair, or simply going along with the crowd like the 'passive' nihilist, he will recognize himself as the sole source of truths and values to live by.

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.

It turns out, in fact, that 'theories of meaning' are typically not about meaning in an everyday or 'folk' sense at all. They are theories designed to compute the truth or assertibility conditions of sentences from their components.

For me, the existentialists are important critics of 'absolutist' claims, and Heidegger and Merleau-Ponty are, at least in their later writings, also exponents of a doctrine of mystery: Being or the 'well-spring' of everything is, for Heidegger, ineffable, just as what Merleau-Ponty called 'Flesh' is for him.

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.

There is no reason at all to think that creatures with very different purposes and concerns would arrive at the scientific image, and no reason at all to accuse such creatures of getting the world wrong - a point that both Chuang Tzu and Nietzsche make when comparing human and animal perspectives.