Slightly off-topic, but I was reading in Bernard Williams's Ethics and the Limits of Philosophy last night and this quote about a difference between deontological and consequentialist ethics caught my attention:

Obligation and duty look backwards, or at least sideways. The acts they require, supposing one is deliberating about what to do, lie in the future, but the reasons for those acts lie in the fact that I have already promised, the job I have undertaken, the position I am already in. Another kind of ethical consideration looks forward , to the outcomes of the acts open to me.