A lot has been said over the past two weeks about blame, and a lot that has been said about it seems to assume that any given crisis generates some fixed amount of blame to be apportioned out to those who are blameworthy.
I see the act of blaming as one of judging culpability for what a person did (or left undone), plus a call (stated or implied) that the person is to be punished. (Depending on the circumstances, the punishment might be a dirty look, or enduring enmity, or imprisonment.)
Now, moral culpability arises within the context of individual moral acts. As a rule, the avoidance or mitigation of a crisis depends on many individual moral acts, committed by many individual moral actors. The negative consequences of a crisis are not themselves the source of a pool of culpability, to be ladled out appropriately.
That some people do see the act of blaming as a matter of dividing up some fixed quantity of blame can be seen in the language they use. Someone earns the lion's share of the blame, or has all the blame hung on him. Some people even speak of proportions of blame -- "he shouldn't get any more than 30% of the blame" -- as though blame were a substance that can be measured.
This suggests that there's more going on when we blame others than judging their culpability. I think speaking of relative blame ("I blame him a lot more than her") adds to the judgment a recommendation of how much energy should be used in pursuit of punishing the people who are blamed. This, in effect, shifts the frame of reference from the general crisis to the individual commitment to the crisis. A person is willing to commit a certain amount of attention, indignation, time, and other resources to following up on a crisis; these resources are finite and non-sharable, so it makes sense to speak of partitioning them in some fashion.
Culpability itself, though, doesn't work that way. Even in the case of one single, discrete sin, there may be more culpability than is directly measurable from the effect of the sin. (Fr. F. X. Lassance identified nine ways we cooperate with evil: by counsel; by command; by consent; by provocation; by praise or flattery; by concealment; by partaking; by silence; and by defense of the ill done.)
If I tell the wicked man that he shall surely die, and you do not speak out to dissuade the wicked man from his way, he (the wicked man) shall die for his guilt, but I will hold you responsible for his death. But if you warn the wicked man, trying to turn him from his way, and he refuses to turn from his way, he shall die for his guilt, but you shall save yourself.
In both cases, the wicked man dies, but the culpability of each person varies -- and the difference in culpability is not minor.
So we should be aware, when we are asking who is to blame, that the amount of blame we're willing to dole out does not necessarily correspond to the sum of each person's (individual and non-transferable) culpability.