Things only 'show up' for us as they do, as Heidegger would put, in and through practical engagements with the world that enable objects to have significance and salience - as hammers, pots, trees or whatever.

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.

My 'heroes' are those - like Chuang Tzu and Heidegger - who recognize that the world of experience is a human world, but recognize too that there is a 'way' or a 'source' to which our lives are answerable.

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.

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.

It's one thing to assent to propositions like 'The way of things is ineffable', and quite another to internalise what it is being gestured at by such propositions, to get a sense or feel for mystery. For me, at least, it is in and through ways of engaging with nature that this sense is intimated. These ways include being in the garden.

I was keen to dispel a familiar misunderstanding: that existentialists somehow relish the alienation of human beings from the world. This may have been Camus's attitude, but it was certainly not that of Heidegger, Sartre and Merleau-Ponty, each of whom tried to show that we can only experience the world in relation to our own projects and purposes. The world is initially one of 'equipment', said Heidegger: it is a world of 'tasks', said Sartre.