We shall find that the metaphysical views offered on behalf of moral conclusions about abortion in defence of those conclusions. Other disputable assumptions separate each moral conclusion from the invoked metaphysical view. It is the defensibility of the other assumptions that is crucial. No metaphysical view cited on behalf of a moral conclusion advances the argument in favour of the conclusion. (Conee 1999, p. 619) In these words Earl Conee sets up a contrast between premisses that do nothing to support an argument's conclusion, and premisses that are crucial to, or substantially advance the argument in favour of', some particular conclusion. Exactly what contrast does he have in mind? As a first shot at what such a contrast might be, compare the role of the second premiss in the following two arguments: