What if you think it's okay to punch Nazis but your principles suggest it's not okay? You'll need to stop punching Nazis or revise your principles. As it is self-evidently true that it's good to punch Nazis, if your principles forbid punching Nazis, that suggests your principles aren't doing the work they're supposed to do.
We might want to refrain from punching Nazis for broadly similar reasons that we grant Nazis free speech. Their words and actions are onerous, but it's important that we give everyone the freedom of thought, speech and, so far as they don't impinge on other people's rights, action. This is good because the state has no right to impose values on us and, more positively, because the free exchange of ideas is the best way to promote a rich, tolerant, pluralistic culture. Except it also seems to have created a situation in which there are Nazis, at which point good sense suggests that we ought to punch them.
There are two common arguments for holding back. The first is to suggest that, tempting though it may be to punch Nazis, things would be even worse if people went around punching them. This counterfactual conditional statement is obviously hard to prove. If the marketplace of ideas produces people who fervently believe in white supremacy and that "The Big Bang Theory" is funny, reason would suggest some kind of intervention is required.
A second reason is that you're embarking on a slippery slope once you accept violence and intolerance even in limited instances, for apparently defensible tactical reasons. Today it's acceptable only to punch Nazis, but tomorrow it could be people who do CrossFit or anyone who references Harry Potter to make a point about politics. That's a real concern, and we constantly need to be vigilant, but toleration is also a slippery slope. Sitting idly by while white nationalists hold seminars and universities practice exclusionary policies and... well, that doesn't turn out so hot, either.
What about ethical consistency? Why is it good to punch Nazis but bad when white supremacists attack antifascist protesters? The answer is so obvious that it takes a tremendous amount of philosophical work to obscure it: because Nazis are bad and antifascist protesters are good. But it can be useful to reduce those different incidents to manifestations of the same basic intolerance, and frame the adjudication of those events as an argument about meta-principles instead of a contestation of basic values.
Given the suboptimum state of the world, you would think the onus would be on exponents of liberal toleration to demonstrate that their sublime principles transcend bad outcomes or that we truly do live in the best of all possible worlds.
When cool rational analysis works every time to preserve the status quo, it's worth asking why, and whose interest that apparent objectivity serves.
By contrast, an enormous amount of work has been done by scholars and activists, with very different methodologies and sometimes competing goals, to trace the distortions and power imbalances and violence of apparently free liberal political structures. This stuff is by now old hat, but a nice thing about hegemony is that you get to ignore the haters.
I came late to the story about the pregnant woman riding in a cage at the back of a bakkie. By the time I read about it, we'd already ascertained a number of mitigating facts, unearthed innumerable historical complexities, reminded ourselves of our nation's convoluted social norms and taken a deep sigh, meditating on how far we've come and how much work there still is to do.
What's a better response to the fact of a pregnant black woman riding in a cage at the back of a bakkie driven by a white man in South Africa in 2017? A careful analysis of the inner logic of social agents embedded in history? Or incandescent rage?
When cool rational analysis works every time to preserve the status quo, it's worth asking why, and whose interest that apparent objectivity serves. After all, if critical thinking, as a reflex, makes things worse - if interpreting the world prevents us from changing it - critical reasoning demands we review the value and purpose of our critical methods.
A weird thing some people are now doing on social media is blaming 'postmodernism' for the ascent of the Trumpian post-truth era. These are often the same people who perpetuated a crude binary between tyranny and the free market, who insisted there is no alternative to punitive neoliberal austerity, who defended policies designed to serve elites with statistical gibberish, and whose elegant mathematical models teach us that actually sweatshops are good. In other words, they systematically lied to us for decades.
This false and lazy distinction between technocratic truth and postmodern nihilism is a nice way of evading critical theory's forensic analyses of the way knowledge is formed and of the interests it serves. There is freedom and there is tyranny, even if our freedom leads directly into the Age of Trump. There is truth and there are special snowflakes' hurt feelings, even when all those truths turn out to be lies and the snowflakes are the only people standing in the way of the fraud those lies have empowered.