Why Apologize and Express Regret?
So far, so good. But on what grounds must erstwhile enemies express regret or apologize for wrongdoings committed during the war? For what ought they to be offered? And are addressees under a duty to accept them?
Not apologizing for one’s wrongs, and a fortiori explicitly refusing to do so, adds to the first wrong the second wrong of indifference to the predicament in which 
victims find themselves as a result of one’s own doing. That second wrong is not merely an insult, it is an injury in its own right, for it betrays a failure to treat the victim as a moral interlocutor.
Agent-neutral regret, for its part, ought to be expressed on the deontological grounds that one cannot be committed to the view that perpetrating those deeds is morally wrong and yet refuse in principle publicly to denounce them: all of us have a pro tanto reason to express regret that wrongdoings were committed and suffering wrongfully inflicted (and in so doing reaffirm one’s condemnation thereof).
Agential regret, for its part, shares one important feature with apologies. Although the agent is not culpable for the wrongful state of affairs, x, about which regret is appropriate, he nevertheless is responsible for it. To express no regret at all, or to express regret as if he were not in any way causally implicated in x, is to fail properly to account for his part in the victim’s predicament. Such a failure is also a failure of respect.
Finally, non-agential (agent-relative) regret admits of slightly different justifications. I said above that benefiting from x makes it appropriate to express regret about the wrongdoing—as does a particular kind of connectedness with perpetrators of the wrongdoing. With respect to benefiting, here again, to express no regret at all about x, and/or to do so agent-neutrally, is to fail to account properly for the fact that one is not situated in relation to x in the same way as a bystander, and that there is a morally salient asymmetry between one’s lot (having benefited from x) and the victim’s lot (having wrongfully suffered as a result of x). That failure, in turn, is not merely a lack of intellectual honesty. It is also a moral failure—the failure of failing properly to acknowledge one’s moral location in relation to a particular wrongdoing, and thereby the victim’s moral location in relation to one’s own.
The second kind of non-agential regret relies on a morally relevant connection between the perpetrators of the crime and the agent called upon to express regret, such that regret, understood as distancing oneself from the wrongdoing, is appropriate. At the bar of cosmopolitan morality, political membership in a transgenerational community cannot alone be one such basis. Sometimes however an open commitment to one’s community’s heritage may give others, notably victims and their descendants, good reasons to fear that one positively identifies with the crimes—unless there is explicit distancing therefrom via the expressing of regret. In this case, expressing regret is warranted, on the simple grounds that instilling fear and distress in others is generally morally undesirable.
Thus far, my arguments for apologies and regret have been, for the most, deontological. But as the point about reassurance suggests, those utterances and relevant practices also admit of an instrumental justification. Admittedly, when they are owed to victims, this is not the main reason why parties should so act: if I apologize or express regret only because I seek peace, and not solely because I believe myself to be under a duty to treat my victim as my moral interlocutor and to distance myself from the wrongdoings, my utterances are not genuine, and thus do not really count as such. Nevertheless, the process of reconciliation does constitute an additional reason for so acting.
I say ‘when those utterances are owed to victims’. However, victims are not owed an apology, and it is debatable whether they are even owed agential and non-agential regret, when they themselves have grievously wronged those who have wronged them. For example, I am not persuaded that the Germans owe regret or apologies for the bombing of Coventry in 1940 to British perpetrators of and beneficiaries of the 1944 bombing of Dresden, and vice versa. Wars offer many examples of reciprocal and grievous wrongdoings. That said, in such cases, we can and should justify joint utterances of (agential) regret, along the lines ‘we/our predecessors should not have done this to each other’, as indicative of a common resolve to work towards peace and a means to facilitate reconciliatory processes. 
By that very same token, however, apologies and expressions of regret are constrained by the imperative not to jeopardize prospects for a justifiedATC peace. If insisting on public acts of that kind or performing them are likely to do so—for example because perpetrators would walk away from the peace negotiations—then one should not do so. This raises the delicate issue of timing: a long delayed utterance might sometimes be insulting for being too little, too late; conversely, a premature utterance, particularly a premature apology, might also be insulting for suggesting that the perpetrators are thereby seeking to block victims’ expressions of legitimate anger.
Note also, furthermore, that what counts as successful expressions may differ from culture to culture. In both interpersonal and personal contexts, apologies are often the outcome of more or less complex negotiations between parties, both of whom have their own understandings of what they will or will not accept. Those understandings are partly shaped by their own cultural values^4 It is therefore part of the duties to express regret and to apologize that they should be discharged in a way that is sensitive to addressees’ cultural practices—at least up to a point: if either regret or, perhaps more likely, apologizing requires self-abasement in certain cultures, we might want to resist doing so.