It says a great deal about Donald Trump that for the second time under his Presidency we are having to ask the question: is it OK to punch a Nazi?

More specifically, after the events in Charlottesville last weekend, we must ask: is it OK to turn up to a legal march, by permit-possessing white supremacists, and physically stop that march from taking place through the use of force if necessary?

The US president has been widely criticised for indicating that he thought the assortment of anti-semites, KKK members and self-professed Nazis were no worse than the anti-fascist counter demonstrators. So for him, the answer is presumably no, it’s not OK to punch a Nazi in this situation.

For others such as Melanie Phillips in the Times, or Telegraph writer Martin Daubney, the left have seemingly become the real fascists.

The argument goes that both sides are extremists and thus both must be condemned equally for violence (skipping over the fact that one of the counter-protesters was killed by a member of the far right, who drove his car into a crowd).

This argument – by focusing on the ideologies of the two groups – distracts from the more relevant issue of why both sides were in Charlottesville in the first place.

The Nazis and white supremacists were marching there because they hate minorities and want them to be oppressed, deported or worse. That is not just a democratic expression of opinion. Its intent is to suppress the ability of others to live their lives and express themselves, and to encourage violence and intimidation.

The counter-protesters were there to oppose and disrupt that march in defence of those minorities. Yes, some may have held extreme left-wing views, but they were in Charlottesville to stop the far-right trying to impose its ideology on others, not impose their own.

So far, the two sides are not equally culpable.

Beyond the ethical debate, there is also the fundamental question of whether it is simply counterproductive to use physical force against a far-right march.

The protesters could, of course, have all just held their banners and chanted back. They could also have laid down in front of the march and dared the “Unite the Right” march to walk over or around them.

Instead the anti-fascists kicked, maced and punched back. That was what allowed Trump to even think of making his attempt to blame both sides at Charlottesville.

On a pragmatic level, there is plenty of evidence from history to suggest that non-violent protest has had a greater impact. From Gandhi in to the fall of the Berlin Wall, non-violence has often been the most effective tool of political movements fighting oppression, achieving political goals and forcing change.

But the success of those protests was largely built on their ability to embarrass the governments they were arrayed against. For democratic states in particular, non-violent protest can be effective because the government risks its legitimacy if it is seen violently attacking people peacefully expressing a democratic opinion.

Unfortunately, it’s a hell of a lot more difficult to embarrass a Nazi. They don't have legitimacy to lose. In fact they gain legitimacy by marching unopposed, as if their swastikas and burning crosses were just another example of political free expression.

By contrast, the far right do find being physically attacked embarrassing. Their movement is based on the glorification of victory, of white supremacy, of masculine and racial superiority, and scenes of white supremacists looking anything but superior undermines their claims.

And when it comes to Nazis marching on the streets, the lessons from history show that physically opposing them has worked. The most famous example is the Battle of Cable Street in London, in which a march by thousands of Hitler-era Nazis was stopped parading through East End by a coalition of its Jewish Community, dockworkers, other assorted locals, trade unionists and Communists.

There was also the Battle of Lewisham in the late 70s when anti-fascist protesters took on the National Front. Both these battles, and that’s what they were, helped neuter burgeoning movements of fascist, racist far right thugs who hated minorities.

None of this is to say that punching a Nazi is always either right, or indeed a good idea. The last time this debate came up was during Trump’s inauguration when "Alt Right" leader Richard Spencer was punched while giving a TV interview. Despite the many, many entertaining memes made from the footage, what casual viewers saw was a reasonable-looking man being hit unawares. He could claim to be a victim.

Charlottesville was different. When 1,000 Nazis come marching through a town trying to impose their vision of the world on it and everywhere else, they don't have any claim to be victims.