Before I get going, I'd like to remind you that I was writing about police violence and systematic injustice against blacks (and others) in the criminal justice system years ago, before it was cool and on your mind. So when you see me talking about protestors' excesses, it's not because I think that's the most important issue, but because it's what I find philosophically interesting now.
On its face, looting seems wrong. Consider the basic doctrine of defensive violence. If someone is attacking you or others, you may use defensive deceit, subterfuge, and even violence back at them, if doing so is necessary to stop them. The principle is a bit more complicated than that, of course. (I discuss the complexities in the second chapter of When All Else Fails.) There are issues about imminent and on-going general threats, how proportional the response can be, what exactly "necessary" means, and so on. (Generally, the necessity requirement is that you can't use a more harmful response when a less harmful response is as effective.)
Still, you are not in general allowed to attack innocent bystanders. If the bully picks on me daily, I can't beat up his cousin or a stranger as a way of making him stop, even if somehow beating up this innocent third person induces him to stop. I can't steal lunch money from an innocent third person to stop that the bully from stealing mine. I can't engage in racist attacks against Koreans to stop white people from engaging in racist behavior toward me.
There may be special cases where this behavior is excusable, such as that you may break into a store to hide if that's necessary to stop someone from abducting you.
One might try to overcome this presumption against hurting innocent third parties in two sorts of ways:
1. Argue that the third parties aren't actually innocent.
2. Argue that the good consequences of looting and riots justify the behavior.
There are smarter and dumber versions of 1. Let's start with the dumber version. On Facebook, you can see people sharing memes that make it seem white people and all black people are part of two big, coordinated moral teams. When some white people mistreat some black people, or vice versa, that's team W attacking team B, and vice versa.
But of course we're not on teams. There are individual people acting wrongly. There is indeed systematic injustice, as my own book on criminal justice documents and diagnoses. But even this systematic injustice is not all white people hurting all black people, but rather specific white people hurting many black people or in some cases specific black people.
Unfortunately, both hardcore racists such as the KKK and many of today's woke folk accept the team sport mentality of ethics. But this way of thinking is a cause of our problems, not a solution. Some British people were awful to some Irish people in the past, so should an Irish person today hate all British people and hold them responsible? Not only does this attitude moral responsibility incorrectly, it leads to further conflict. On the contrary, if you could wave a magic wand that would stop people from thinking of themselves and others as part of ethnic and racial teams, you'd do the world a big favor by waving it.
The smarter version of 1 is to say that people are complicit. Everyone is complicit in these injustices because they could have worked to stop them or perhaps could have stopped them, but they instead tolerated them or even indirectly aided them.
But this is problematic for a few reasons, too.
For one, complicity actually means involvement, not failing to act. Yet most of the time, when people say others are complicit, what they mean is that these others could have stopped the problem but didn't, not that they contributed to the problem.
Second, not everyone is complicit. Some people have in fact worked to stop systematic injustice, and looters and rioters have no idea whether the person whose small business they're destroying is complicit or not. Some people have or had very little power. Some people are new the country and haven't had a chance to do anything. And so on. It's not as though the rioters first document individual people's moral responsibility and then target those who have it coming. (If you do, though, please remember that by this line of argument, my neighbor's houses may be targeted but not mine. Remember, protestors, I was working on this years ago before most of you even cared. Thanks.)
Third, the bigger problem is that if we're going to say that nearly every person in the US is complicit in various injustices, this once leads to the perverse conclusion that I am justified in looting your house and attacking your businesses. After all, you all are not merely complicit in the criminal justice system's systematic mistreatment of blacks and the poor. You are complicit in the even worse injustice of closed borders and how immigrants are treated. At any rate, the Open Borders crew and I will be passing through Cambridge, MA, this weekend to loot any house with a pro-Biden or pro-Trump sign. Any car with a Bernie sticker is gonna burn.
Regarding 2: The consequentialist argument is weak for at least two reasons as well. First, it's far from clear that looting and rioting help produce desired consequences. The empirics are complicated, and there is strong evidence that people react to such behavior by voting for law and order candidates. If I were Trump, I might encourage such looting as a way of drawing people back to me. "Look, the Democrats will let your homes and businesses burn. I will restore civilization." It's an effective message, and there is good evidence it works. It may not be enough to get him re-elected, but it appears to be helping him already. (Can we loot the looters' houses because of their complicity in re-electing Trump?)
But, regardless of the empirics, you get the same problem as the previous argument: it proves too much. If we may riot and loot to protest police murders, why can't we riot and loot for countless other causes, including higher stakes causes, such as climate change or closed borders?
At any rate, I'm not saying all rioting and looting is wrong. Burning and looting the local police station in many cities and towns is probably justifiable. This is too simple, but in general, since the government is acting wrongly, you may attack its property, but not the property of third parties.