The only difference is that Brown would have to let 1 die to save 5, whereas Green would have to kill 1 to save 5. But this difference is morally critical, for it is obvious that Brown should choose life for 5, whereas Green should choose life for 1. We must now ask why the distinction between killing and letting die seems morally relevant in the Brown and Green cases, but not in the Smith and Jones cases. Foot argues that the answer lies in the kinds of rights and duties associated with killing and letting die. Rights can be divided into 2 types, negative and positive.
Positive rights are our rights to goods and services, such as our right to food and medical care.
Foot argues that the difference between the Smith and Jones cases is that Smith fails in his negative duty not to kill, whereas Jones fails in his positive duty to lend assistance. The moral significance of this difference is only academic, however, because in the circumstances described it is equally wrong to fail in either duty. The cases of Brown and Green are more complicated. If Brown lets 1 person die to save 5, he fails in his positive duty to provide the 1 person with medical care. If Green kills 1 person to save 5, she fails in her negative duty not to kill the 1 person.