While Trump has gained much by weaponizing incivility and Maxine Waters seems to have gained little or even lost in her efforts to do so, there remains the question of the ethics of this practice. After all, there is a distinction between a tool that works well (or poorly) to achieve an end and the morality of that tool.
One obvious approach is to embrace the ethics of Immanuel Kant. Kant was rather focused on the dignity and worth of such beings. One of his injunctions was that rational beings must never be treated merely as means to an end, but must always be treated as ends themselves. To treat a rational being with incivility to gain a political advantage would seem to violate this tenet of Kantian ethics. It could, perhaps, be argued that a rational being could be treated with incivility while still respecting its moral worth as a rational being. After all, Kant does claim that a being must prove worthy of happiness by having a good will and it could be argued that a rational being that lacks the good will could be treated with incivility. However, this seems to be rather a stretch—for Kant, a rational being would not forfeit its moral status as an end even if it were evil.
Another obvious approach is the consequentialism of John Stuart Mill’s utilitarianism. On this view, beings count in terms of their ability to experience happiness and unhappiness. This is because for Mill, an action is right to the degree it generates more happiness than unhappiness for the beings that matter. An action is evil to the degree it generates more unhappiness than happiness.
On Mill’s view, the harms done by the incivility would be weighed against the benefits. Unlike under ethical egoism, for Mill this calculation would include all sentient beings impacted. For the ethical egoist, only their happiness and unhappiness matter. Weaponizing incivility seems to have generated considerable positive value for Trump, his supporters and those who have benefited from his election. However, it has clearly harmed those who have been targeted as the objects of Trump’s incivility. Incivility invites retaliation, so while Trump is largely sealed away from reprisal for his incivility, those associated with him can be targeted, such as Sarah Huckabee Sanders and Alan Dershowitz. As such, they are also harmed, albeit indirectly, by Trump’s weaponization of incivility and directly by those who use it against them. While two wrongs do not make a right, those associated with Trump have little moral ground on which to stand when they are subject to incivility—they have chosen to associate with Trump and do not condemn his incivility. To use an analogy, imagine that captain of a sports team is an incredibly bad sport, plays too rough and cheats. While their teammates might not be as bad, they simply go along with the behavior and the referees allow it all to happen. While the opposing teams should not engage in that behavior, the members of the bad captain’s team would have little ground for complaint if opposing teams started retaliating against them if they could not reach the badly behaving captain. Ideally, of course, everyone should be civil—but, as with violence, those who start the incivility have no grounds for complaint if they receive what they have given.
There is also the broader concern beyond the individual targets, specifically the impact on what people regard as social norms and acceptable behavior. There has been considerable attention paid to incivility in the workplace and the research shows that this poor behavior is costly. While there are differences between the workplace and society, it would make sense that many of the harms of incivility in the workplace would also take place in broader social contexts. As noted above, this is already happening. One obvious consequence is that incivility makes political compromise and cooperation between the parties even less likely. Going back to the sports analogy, what enables competing teams to play the sport and not have it degenerate into a brawl is a basic civility. The same is presumably true in politics. The challenge is, of course, that both teams must agree to be civil—if one team breaks the rules and the referees do nothing, then the civil team is at a disadvantage. It could, of course, be argued that the other team should stay civil even in the face of incivility—this is, after all, a key part of good sportsmanship. It could even be contended that by remaining civil, the civil team will shame the other team into returning to civility or, more likely, that the booing of the fans will force them to behave better. The same could be argued in the case of politics—the left should stay civil despite what Trump and his fellows do. In doing so, it could be claimed, they take the moral high ground and perhaps the public will respond by rejecting incivility in favor of civility. In terms of utilitarian ethics, the key question is whether retaining civility in the face of incivility would create more happiness than unhappiness or the reverse. I am inclined to think that two wrongs would merely make things worse. That said, this could be analogous to refusing to respond with violence when attacked—pacifism might occupy the moral high ground, but that ground tends to be splattered with the blood of pacifists.