Okay, the argument so far: Anselm has contended that humankind has fallen into sin by failing to render to God the honor due him (i.e. obedience). As a result we threaten to fail to acheive God’s intended purpose for us, namely, being part of the “celestial estate” and consequently we disrupt the order and beauty of God’s good creation. God won’t suffer the order of creation to be disrupted, since otherwise he would not be all-good and all-powerful. For the order to be restored and the goodness of creation to be upheld sin must be punished or satisfaction must be made for it. Human beings, already owing everything they have to God, are unable to make satisfaction for sin. And yet if God were simply to punish sin his purpose for humankind – their sharing in the celestial estate – would be frustrated. Therefore, God will make satisfaction for sin.

In Book Two, Anselm turns to discuss in more detail how it is that God makes satisfaction for sin. In Book Two, Chapter Five Boso raises the objection that saying that God must make satisfaction for sin seems to put God under the constraints of some kind of compulsion or necessity. Moreover, if God acts of necessity why should we be grateful for what he does?

But, Anselm replies, this isn’t an absolute necessity, but only necessary given that God has purposes for human beings and will do whatever is necessary to make those purposes effective. God’s original grace to us is our creation and that he destines us for eternal life; how much more grace, then, does he show in that he stoops to bring us to that destination even after we have fallen into sin?

Much more, therefore, do we owe all thanks to God for completing his intended favor to man; though, indeed, it would not be proper for him to fail in his good design, because wanting nothing in himself he begun it for our sake and not his own. For what man was about to do was not hidden from God at his creation; and yet by freely creating man, God as it were bound himself to complete the good which he had begun. In fine, God does nothing by necessity, since he is not compelled or restrained in anything. And when we say that God does anything to avoid dishonor, which he certainly does not fear, we must mean that God does this from the necessity of maintaining his honor; which necessity is after all no more than this, viz., the immutability of his honor, which belongs to him in himself, and is not derived from another; and therefore it is not properly called necessity. Yet we may say, although the whole work which God does for man is of grace, that it is necessary for God, on account of his unchangeable goodness, to complete the work which he has begun.