First off, I highly recommend readers watch this short, entertaining clip. It's from a talk by Derrick Jensen, a radical environmentalist. While Jensen is not a communist, I think his work on violence as well as his ecological views are very important.
The first argument I'd like to address is the one that goes something like this: We shouldn't stoop down to their level, we are better than that. You'll hear this a lot from anti-war activists. I haven't heard it often from Marxists, so I won't spend too much time here. Communism is not a social club, and it isn't a moral high ground. On the contrary, those actively engaging in revolution will find themselves making incredibly tough decisions on a daily basis. The Marxist position is unique in that it grants practical concerns grounded in reality priority over theoretical constraints. If something advances the cause of the working class, than we ought to do it. The goal is to beat the bourgeois, not to assuage our own egos by being "better" than them.
Another common argument is that violence is not effective. As Jensen points out in the above video, violence is dreadfully effective, that's why they use it. The threat of violence is why you pay your rent, it's why you follow the speed limit, and it's way so many people are rightfully afraid to act out. Capitalism cannot exist without widespread violence. Otherwise, why would anyone participate? People don't give up their land and sell their lives for pennies on a whim. They do these things because they are systemically forced to do so, and they know that those in charge won't hesitate to hurt or kill them. The capitalist state takes full advantage of the use of violence, and we should too. Without the use of violence, revolution simply is not possible.
The historical materialist position necessitates the use of violence. If we look at past uprisings and revolutions, we find that all of them involved violence in some way. Socialist revolutions are especially bloody because the ruling class has so much more to lose. It's not simply another regime change. The bourgeois stand to lose everything. It's naive to presume that they might just give in to our demands out of the kindness of their hearts. Historically, we see that they will fight tooth and nail to hang on. Every single successful socialist revolution has involved the use of violence and the forceful suppression of the bourgeois. That alone should be enough to convince a Marxist that armed struggle is necessary.
There's another, more nuanced argument against the use of violence, particularly in the United States. This argument holds that violent revolution is not possible in the West because of how powerful and technologically advanced Western professional armies are. This is a more practical concern, and it should at least give us pause to assess what we are up against. It is true that Western powers enjoy an enormous military advantage over everyone else. However, has this not been so throughout history? History is ripe with examples of ill-equipped forces successfully waging war against technologically advanced opponents. This advantage is certainly not a recipe for 100% success. This argument for nonviolence also ignores the incredible potential for asymmetric warfare in the West. Consumerism has placed a lot of advanced technology in the hands of ordinary people. It has also placed a lot of high quality fire arms in the possession of the working class. These are advantages that past socialist revolutionaries did not enjoy. If anyone is skeptical that the working class can produce high quality devices for the purpose of warfare, I would recommend they check out the DIY electronics movement that is booming right now. People are making their own personal drones for a fraction of the cost it takes the military to produce one. If the Western working class were to militarize, it could easily produce radars, anti-aircraft weapons, anti-tank mines, and even guided missiles. The technology is there, and much of it is really cheap. So we really shouldn't be too concerned by this argument. With a highly specialized working class, we can expect masterful uses of technology once the masses attain class consciousness.
I find the nonviolent position to be one of privilege. Most of the world faces acts of extreme violence on a daily basis. When you're facing a loaded gun, you don't really have time to consider the moral implications of fighting back. It's (likely) natural to feel aversion at the thought of harming another human being, but how else do you stop a class hellbent on harming everyone in order to line its pockets? If revolutionary use of violence bothers you, it's important to remember who is doing the oppression. We didn't ask for this, it was forced upon us. It's not out of blood thirst that communist engage in armed struggle, it's out of historic necessity. As Marx said,
“Men make their own history, but they do not make it just as they please; they do not make it under circumstances chosen by themselves, but under circumstances directly encountered, given and transmitted from the past. The tradition of all the dead generations weighs like a nightmare on the brain of the living.”