Consider what Michael Rea identifies as “common to the most well-known versions of the satisfaction theory” of the atonement:
The satisfaction theory start with something like the following characterization of the human predicament: Our sin has put us in the position of owing God something that we cannot possible repay on our own. From birth, we have owed God a perfect life. By sinning we have failed to give him his due, and we have also rendered it impossible for him to receive his due from us (since we can’t take back our sin and thus give him the perfect life we initially owed him). Moreover, we have affronted God by failing to give him what we owe; so we now owe something further to make up for the affront But we cannot compensate God for the affront for precisely the same reason that we cannot make restitution for our sins: anything we tried to offer up as restitution or compensation would only be what we already owed in the first place. [“Introduction,” in Oxford Readings in Philosophical Theology (Oxford, 2009), pp. 14-15.]
The starting premise—shared by other theories of the atonement as well—is that “we owe God a perfect life.” In saying we owe God a perfect life, presumably what is meant is that we have an obligation or duty before God to live a morally perfect life, one free of sin. And we incur debt—i.e., blameworthiness—by failing to give God his due, failing to fulfill our duty or obligation before God.
But why think this starting premise is true? How is it that just by being born we are under obligation to live and offer God a perfect life and are blameworthy for failing to do so? There is the vague thought that the premise might be conceptually entailed by facts about our relation to God. But it’s hard to see what those facts might be. God is our morally perfect creator and sustainer, but how does it follow from this that we owe him a morally perfect life? It’s much easier to see difficulties with the premise. Here are two:
1. It is often taken as axiomatic in ethics that “ought” implies “can.” But if we mere humans cannot live a morally perfect life and cannot repay God what we owe him, then it’s not true that we ought to live a morally perfect life or repay God what we owe him. But rejecting the axiomatic ought-implies-can principle doesn’t seem like a promising route.
2. Suppose a mere human can live a morally perfect life, and someone in fact does. Is she not praiseworthy for living such a life? I think so. But one is not praiseworthy for doing one’s duty or fulfilling one’s obligations. Doing what is required is not praiseworthy. And living a perfect life cannot ex hypothesi be supererogatory.
So the premise clashes with two potent moral intuitions—that ought implies can and that one would be praiseworthy for living a morally perfect life. Is the premise essential to theories of the atonement? What reasons are there for thinking the premise is true? And, most interesting: is an alternative, perhaps more modest premise available?