Four Types of Moral Luck
Thomas Nagel identified four kinds of moral luck in his essay. The kind most relevant to the above example is "resultant moral luck".
Resultant Moral Luck (Consequential)
Resultant moral luck concerns the consequences of actions and situations. In the above example, both drivers were affected by resultant moral luck in that a particular set of circumstances turned out in two different ways: in one situation, a pedestrian appeared on the road; in the other, the pedestrian did not.
Circumstantial Moral Luck
Circumstantial moral luck concerns the surroundings of the moral agent. The best-known example is provided in Nagel's essay. Consider Nazi followers and supporters in Hitler's Germany. They were and are worthy of moral blame either for committing morally reprehensible deeds or for allowing them to occur without making efforts to oppose them. But, if in 1929, those people were moved to some other country, away from the coming hostilities by their employers, it is quite possible that they would have led very different lives, and we could not assign the same amount of moral blame to them. It is down, then, to the luck of the circumstances in which they find themselves.
Constitutive Moral Luck
Constitutive moral luck concerns the personal character of a moral agent. There can be little argument that education, upbringing, genes and other largely uncontrollable influences shape personality to some extent. Furthermore, one's personality dictates one's actions to some extent. Moral blame is assigned to an individual for being extremely selfish, even though that selfishness is almost certainly due in part to external environmental effects.
Causal Moral Luck
Causal moral luck, which equates largely with the problem of free will, is the least-detailed of the varieties that Thomas Nagel describes. The general definition is that actions are determined by external events and are thus consequences of events over which the person taking the action has no control. Since people are restricted in their choice of actions by the events that precede them, they should not be held accountable or responsible for such actions.
Thomas Nagel has been criticized[who?] for including causal moral luck as a separate category, since it appears largely redundant. It does not cover any cases that are not already included in constitutive and circumstantial luck, and seems to exist only for the purpose of bringing up the problem of free will.[1]
Alternatives
Some philosophers, such as Susan Wolf, have tried to come up with "happy mediums" that strike a balance between rejecting moral luck outright and accepting it wholesale. Wolf introduced the notions of rationalist and irrationalist positions as part of such a reconciliation.
The rationalist position, stated simply, is that equal fault deserves equal blame. For example, given two drivers, both of whom failed to check their brakes before driving, one of them runs over a pedestrian as a consequence while the other does not. The rationalist would say that since both of the drivers were equally at fault in failing to check their brakes, it should make no difference that one of them was lucky in not hitting a pedestrian while the other was unlucky – moral fault is independent of consequence. Since the fault here is equal, the agents should receive equal blame.
The consequentialist position argues that equal fault need not deserve equal blame, as blame should depend on the consequences. By this logic, the lucky driver certainly does not deserve as much blame as the unlucky driver, even though their faults were identical.
Wolf combines these two approaches in trying to reconcile the tensions associated with moral luck by introducing the concept of a virtuous agent. A virtuous agent should accept that he has a special connection with the consequences of his actions, including equal-fault cases (such as the lucky/unlucky drivers above), and even in no-fault cases. This argument essentially retains the rationalist claim that equal fault is equally deserving of blame while also retaining the consequentialist claim that different outcomes should result in moral agents feeling and acting differently.
It is important to underline the distinction between internal and external moral blame or praise. Wolf believes that the outsiders should blame the lucky and unlucky drivers equally despite their intuition that the two of them should not feel equally bad (i.e., the unlucky driver that ran over a pedestrian should feel worse). However, the unlucky driver himself should voluntarily accept the notion of the special connection between his actions and the unfortunate consequences, and assign more blame to himself than the lucky driver should.