Those interminable debates about whether criminals are to blame for their crimes or whether we should look to their circumstances are now repackaged as a standoff between those who want to hold terrorists responsible for their atrocities and those who look to root causes. The right answer, of course, is “both”. But here’s a simple and plausible model, entirely a priori , to help us to think about things.
Imagine a population who vary in their susceptibility to pressure. We can call the property in which they vary “virtue”. Some are so virtuous that no matter what the pressure, they never perform an evil act. Some are so vicious that even if the pressure is negative, they do vile things just for the hell of it. Most people are in between (since virtue is normally distributed). As pressure—caused by poverty, social dislocation, military occupation, whatever—rises, more and more of the population switch, given their underlying propensities, from virtuous to vicious actions.
When they perform those vicious actions, whatever the pressure, they should be held responsible. But we also want to say something about politicians (and others) who increase or decrease the pressure. Deliberately increasing the pressure—perhaps so as to attract political support from fearful voters—should also be something that gives rise to an ascription of responsibility.
Now it might seem odd to say that both the pressure increaser and the perpetrator are morally responsible for a vicious action. Or it might seem exculpatory to make that move since it might seem to reduce the perpetrator’s responsibility to the extent to which it accepts the pressurizer’s. But, happily, the mathematics of moral responsibility isn’t like that: two people can both be 100 per cent responsible for the same crime.
If you doubt that, consider the case of the drowning child whom ten swimmers—of which you are one—are well-placed to save. If the child drowns through your inaction are you only 1/10th responsible? If there had been 10 more would-be rescuers, would your responsibility have decreased proportionately? Clearly not: you are, in each case, completely responsible for the child’s death (and so is each of your fellow bystanders).
Obviously, there can be degrees of responsibility for crimes or acts of terrorism. The crucial point is, I think, that those degrees needn’t sum to 1 or to any other particular figure. And in blaming the perpetrators we needn’t be afraid to assign however much responsibility is due to those who produce the circumstances in which they perpetrate.