'Nazism' and 'Heidegger' are deeply problematic figures. The former brought into existence a novel machinery of totalitarian government, harnessed to industrial capitalism and modern technology, that within twelve years had murdered more than six million people in its extermination programmes, subjected millions more to brutalised slave labour or to forced migrations across and beyond Europe, and in a war of its own prosecution had killed nearly four million troops on the German side alone, whilst reducing the German economy, its major cities and infrastructures to ruin. The list of indictments, much longer, can at least begin there.

Martin Heidegger, the German philosopher, is problematic for different reasons. In his early work of the 1920s he proposed a radical rethinking of human subjectivity, questioning what it might mean to have one's existence as a 'human being'. In this he rivals other modern, innovating discourses on subjectivity, for instance Freud's psychoanalysis and scientific psychology.

Also, Heidegger proposed a 'thinking', distinct from 'philosophising', which relentlessly questioned the foundations of Western philosophy. The stakes are high, if we take that tradition to span two and a half thousand years. Reason, logic and truth, for instance, might no longer be allowed their assurance.

Heidegger had an even more ambitious project: the question of being. He interrogated not just human being, but being 'in general', the fact that entities have their existence. He offered to ontology, the grand tradition of philosophical speculation on being, a radically new beginning.

The encounter between Heidegger's thinking and Nazism has been described as disastrous, even monstrous. Metaphors of collision lend themselves—as if in some train crash, perhaps, productive or not, the most innovative philosopher of the twentieth century lent his thinking to one of its most notorious political regimes. The encounter between these two, blunderingly aligned or grossly impacted, has had repercussions ever since.