First, the defender of constitutive moral luck might argue that a person ought not be praised or blamed for actions proceeding from firm and stable dispositions (i.e. moral habits), since the person could not do otherwise. So a misanthrope would not be culpable for loudly berating his waitress for a minor mistake with his meal, and a brave soldier would not be praiseworthy for risking injury to save fallen comrades. Neither could even imagine doing otherwise, thanks to their respective moral characters. On this view, even if person is responsible for his moral habits, he would not be responsible for the actions generated by them. So the moral luck wouldn’t be the result of praise or blame for one’s character per se but rather for the actions proceeding from it.
Most obviously, this argument confuses the idea of “I just couldn’t imagine doing other than X” with “I actually couldn’t do other than X.” The former is a dramatic but literally inaccurate expression meaning only that the moral choice in a given situation is so clear that alternatives need not be seriously considered. The latter, in contrast, denies the person any actual power to do otherwise. Stable moral dispositions offer only the former (i.e. moral clarity) not the latter (i.e. psychological determinism). More fundamentally, the argument seriously misunderstands the psychology of moral habits. It presupposes a mechanistic model of habituation in which the actions proceeding from entrenched moral dispositions are automatic and unthinking responses on par with reflexes. That mechanistic model would be incompatible with moral responsibility—but it’s not the model at work for Aristotle, nor even a plausible common sense view.
For Aristotle, virtuous action requires more than just the right outward act: that act must be generated by certain kinds of inner states, including choice of the act. Aristotle makes this point explicitly in limiting his analogy between the arts (e.g. bricklaying and lyre-playing) and moral action. He observes that “the products of the arts have their goodness in themselves, so that it is enough that they should have a certain character.”69 In contrast, “if the acts that are in accordance with the excellences have themselves a certain character it does not follow that they are done justly or temperately.”70 The person acting virtuously must be “in a certain condition” when he acts virtuously, namely (1) “he must have knowledge,” (2) “he must choose the acts, and choose them for their own sakes,” and (3) “his action must proceed from a firm and unchangeable character.”71 These three conditions make clear that Aristotle does not regard well-entrenched moral dispositions as contrary to informed rational choice, as the mechanistic model of habituation would.
Julia Annas explains Aristotle’s view of the relationship between choice, knowledge, and habit in The Morality of Happiness, observing that the mechanistic view of moral habits “stems from a failure to recognize the internal complexity of virtue, particularly the way in which moral dispositions are developed and implemented by choice.”72 Virtues are developed by “repeated choices” of proper action based upon “deliberation and decision,” not “mindless” techniques like “mere repetition, rote learning, [and] going through the motions.”73 For example:
…if I am thoroughly honest, and decide now not to take something to which I am not entitled, this is itself a choice. My past choices have built up a disposition to be honest, but my present decision is not just a reflex determined by that disposition—it is my endorsement of that disposition. The disposition is not a causal force making me choose; it is the way I have made myself, the way I have chosen to be, and in deciding in accordance with it, I endorse the way I have become.74
In general, “the increasing consistency of behavior and response that builds up as [the process of habituation] happens is … not a non-rational force threatening the agent’s next exercise of rationality.”75 Instead, moral dispositions increase the “effectiveness of the agent’s rationality” since they are “the result of her deliberations and decisions.”76 So moral dispositions do not eliminate choice: they merely prime a person to act according to his prior knowledge (e.g. that stealing is unjust) and prior commitments (i.e. to treating people justly), often with the help of via moral emotions (e.g. revulsion at the prospect of the deception required for theft). Notably, this choice-based understanding of moral dispositions is consistent with the common sense view, particularly with the idea that a person (including oneself) is always capable of acting “out of character,” even if such is highly unlikely.
So constitutive moral luck cannot be plausibly grounded in a view of moral dispositions as deterministic causes of actions. On the standard (i.e. Aristotelian) view, the person who has cultivated firm moral dispositions—whether virtues or vices—must still choose his individual actions. As such, he is justly held responsible for them.