This isn’t normal. Security guards in the front row. Security guards at the door, and out in the corridor, and out on the street, reinforced by the police. Barriers. Bag searches. And the faint sound, through the thick walls, of protesters screaming and shouting. One of the organisers of the meeting sums it up well: “Welcome to Fort Knox,” he says.

The reason for the security is we’re at Edinburgh University for a screening of Adult Human Female. There have been two attempts to show the film already, the last time in April when around 200 people shut it down. I was there that day and one of the people trying to get in, an octogenarian called Flora Brodie, told me she had every right to see the film. The protesters told me she had no such right and were prepared to use force to prove it.

Read more: Adult Human Female: Edinburgh University screening goes ahead

Adult Human Female has become so controversial because it discusses the changes that have happened in society around trans rights. The people who contribute to the film say gender self-ID has had a negative impact on single-sex spaces for women, including prisons and toilets; the people who object to the film say it denies the existence of trans men and women and is hateful. Ahead of this week’s screening, a statement signed by 26 university groups said that by showing the documentary, the university was endangering the well-being and safety of trans students.

So deep is the divide I assumed there was a chance the third attempt by Edinburgh Academics for Academic Freedom to show the film on Wednesday would also be closed down but the university told me beforehand they had the measures in place to ensure it went ahead. And they were right. Like everyone else, I had to prove who I was, my bag was searched, and there were six layers of security between the protesters and the lecture hall.

But the obvious question is how we got here: the point where this level of security is needed for the screening of a film in which people discuss views they are perfectly entitled to hold. One of the speakers in the discussion after the film said universities should be places where new ideas can be robustly examined and that the level of security required on Wednesday should be unthinkable on a campus. Absolutely.

The film is also not what its critics say it is. Yes, it goes into uncomfortable areas, but it discusses them calmly and intelligently. It discusses the difference between sex and gender, it expresses concern about the effects on women’s rights and gay rights of changes to the culture and law on trans issues, and it argues that the belief that trans women are women has taken hold before there has been a chance to properly examine it. The protesters say it is thinly-veiled bigotry and contempt for a minority and endangers the safety of transgender people, but I’ve seen the film now, and it isn’t and it doesn’t.

As one of the participants also said at the event, the hyperbolic language about bigotry is making things worse. I asked a question on the night about possible compromises and whether the panellists want to “roll back” on the biological men who are currently coming into women’s spaces and I got robust pushback from the audience and that’s fine – discussion can be robust. But as one of the speakers said, we’re still a long way from any kind of compromise because discussion is being shut down by protest.

Read more: Scotland is much nicer than the rest of the UK (not really)

So Edinburgh, and other universities, need to do more. For example, when a letter such as the one accusing the organisers of Adult Human Female of being bigoted is distributed to thousands of staff and students via the university email, there should be a right of reply. There should also be a senior person on campus with responsibility for free speech who can step in and fix any issues as and when they happen.

And what would the alternative be? More events ringed by heavy-duty security? As we left on Wednesday, the protesters screamed at us from behind a barrier: “No terfs on our turf!” but at some point, sooner or later, this will have to stop. They will have to sit in the room and talk rather than stand outside and shout. They will have to accept the principle of free speech. “No debate” they say. But they’re wrong. Debate. Debate. Debate.