'If I am walking past a shallow pond and see a child drowning in it, I ought to wade in and pull the child out. This will mean getting my clothes muddy, but this is insignificant, while the death of the child would presumably be a very bad thing.

The uncontroversial appearance of the principle just stated is deceptive... For the principle takes, firstly, no account of proximity or distance. It makes no moral difference whether the person I can help is a neighbour's child ten yards from me or a Bengali whose name I shall never know, ten thousand miles away. Secondly, the principle makes no distinction between cases in which I am the only person who could possibly do anything and cases in which I am just one among millions in the same position.'

Peter Singer's (famous, and much disputed) contention in 'Famine, Affluence and Morality' (1972) may have acquired a new, literal force this week with the widespread dissemination of images of the drowned corpse of a three-year-old Syrian boy washed up on a Turkish beach. The pictures don't alter Singer's argument one way or the other, but reduce the perceived distance between Western Europe and the Eastern Mediterranean.

The Daily Mail is displaying its usual cognitive dissonance in response to the 'migrant crisis', leading with 'Despair of father of tiny migrant brothers washed up on Turkish beach as tragic details emerge of how family fled Isis siege of Kobane to start a new life in Europe' but also running stories headlined: 'Number of migrant children entering Britain alone continues to surge as 100 youngsters are handed to Kent County Council in just ONE MONTH' and 'Revealed: The deadly new tactic used by migrants to bring Eurostar trains to a halt so that they can sneak on board.' As Stalin didn't put it, one dead refugee child is a tragedy; 100 living refugee children is a statistical surge.

But even on the crudest moral reckoning (you break it, you pay for it), Syrian refugees are Britain's responsibility, since the catastrophe in Syria is in part a consequence of the 2003 invasion of Iraq.