Defining supererogation

Sometimes supererogation is defined by a conjunction of a positive evaluation of performing the action and a denial of a negative evaluation of non-performance. For instance:

1. The action is good to do but not bad not to do.

2. The action is good to do but not wrong not to do.

3. The action is praiseworthy but omitting it is not blameworthy.

It seems to me that all such definitions fail in cases where there are two or more actions each of which satisfies one’s obligations.

Suppose a grenade has been thrown at a group of people that includes me. There is a heavy blanket nearby. Throwing the blanket on the grenade is unlikely to save lives but has some chance of doing so, while jumping on the grenade is much more likely to save multiple lives. I am obligated to do one of the two things (there is no time to do both, of course).

I throw the blanket on the grenade. In doing so, I do something good and praiseworthy. And omission of throwing the blanket is neither bad, nor wrong, nor blameworthy, since it is compatible with my jumping on the grenade. But clearly throwing the blanket on the grenade is not supererogatory!

One might object that we should be comparing the throwing of the blanket to not doing anything at all. And if we do that, then the action of throwing the blanket does not satisfy the definitions of supererogation: for it is good to throw the blanket, but bad not to do anything at all. However, if that’s how we read (1)–(3), then jumping on the grenade isn’t supererogatory either. For while it is good to jump on the grenade, to do nothing at all is bad, wrong and blameworthy.

It is clear what goes wrong here. In a case where two or more actions satisfy one’s obligations, it can’t be that all the actions are supererogatory. The supererogatory action must go above the call of duty. It seems we need a comparative element, such as:

4. Action A is better or more praiseworthy than some alternative that satisfies one’s obligations.

I think (4) is not good enough. For it misses the altruistic aspect of the supererogatory. Consider a case where I can choose to make some sacrifice for you to bestow some good on you, and I am morally required to make some minimal sacrifice s₀. However, there is a non-linear relationship between the degree of sacrifice and the good bestowed, such that the good bestowed increases asymptotically, approaching some value v, while the degree of sacrifice can increase without bound. Once the amount of sacrifice is increased too much, the action becomes bad: it becomes imprudent and contrary to one’s obligations to oneself. But as the amount of sacrifice is increased, presumably what eventually starts happening is that before the action becomes actually bad, it simply ceases to be praiseworthy.

Let s₁ indicate such a disproportionate degree of sacrifice: s₁ is not praiseworthy but neither is it blameworthy or contrary to one’s obligations. Then, s₀—the minimal amount of sacrifice—becomes supererogatory by (4). For s₀ is praiseworthy, since it is praiseworthy to make a morally required sacrifice, and hence it is more praiseworthy than s₁, since s₁ is not praiseworthy. But s₁ satisfies one’s obligations. So, the minimal degree of permissible sacrifice, s₀, satisfies the definition of the supererogatory. But that’s surely not right.

I don’t know how to fix (4).