Back in the 1980s, I used to spend a lot of time with a journalist. My friend Tim, who sadly died more than 20 years ago, was a local hack. He was a sub and he loved to collect improbable headlines.

The one that always makes me chuckle to this day was, ‘Awful truth found lurking underneath clothes.’ I can’t remember what that truth was. But I had cause to reflect on it at an event at the Edinburgh Book Festival last night.

The event brought together three very different discussants, Matthew D’Ancona a journalist, Coral Dando, a scientist and Margie Orford, a novelist to talk about the post truth moment that we may or may not be living in.

Matthew has written a book about this and in his opening remarks, he referred to a previous time before post truth and fake news. This was the golden age when if journos told us what was lurking underneath those clothes, we believed them.

This wasn’t just pre Trump and pre Brexit, it was pre bank bail-out, expenses scandal and hacking. The list doesn’t stop there of course but you know the story. Back then we believed people. Of course, it’s not as simple as that and Matthew wasn’t suggesting so.

Coral brought a fascinating glimpse into the world of forensic science to the discussion and Margie the perspective of a truth seeking novelist. So many questions there in an instant. Not the least of which is, what is truth? Let alone post truth. Does science tell the truth? Is fiction true in a way that non-fiction isn’t?

We can debate the truth of the post truth moment. But there’s undeniably something going on isn’t there? And it’s got quite a lot to do with trust. Indeed, there’s plenty of attitudinal evidence to suggest that trust in some of our cherished institutions has been on the decline. In our recent truth seeking we have lost faith in some of those who were previously pillars of truth telling, journalists included.

The opening and closing question last night was about whether we can rebuild trust. I was one of a minority of people who thought that we could. The proportion grew a little but the sceptics still had it.

In truth, I have my doubts but I want to believe we can. I’m a glass half empty optimist kind of a person. It looks bleak out there sometimes but we’ve got to hope, haven’t we? And I took comfort from the event because in a sense the answer was staring us in the face. We can rebuild the trust if we talk to each other.

One of the suggestions to emerge was the idea of a manifesto for truth and indeed doubt. All that got me thinking about what my manifesto for truth might look like and how we can do it. Because as we were rightly reminded last night we are all players. If it’s true we are all in this mess, we can all do something to get out of it.

My manifesto might start something like this.

• Read people you disagree with. I’m left of centre but have read the Spectator for 30 years. It’s not that I don’t like the New Statesman. Far from it. But I can’t understand the world by approaching it from one angle.

• If you’re on social media, follow people not in your tribe. Never mind retweets aren’t necessarily endorsements. Go out of your way to retweet pieces you don’t agree with but make an interesting case.

• Focus on finding a way through. After Trump was elected I wrote about so called identity liberalism, to see if there was an opportunity for dialogue. It may have been the quality of my argument but I was struck by the fact that it clearly had limited appeal for some.

• Take care as much care about the form as the content of discussion. In short, don’t shout. There was a moment last night when it almost got shouty and it was, for me at any rate, the least illuminating and enjoyable part of the discussion.

• Accept that you don’t always know and that others don’t either. It’s fine. We don’t have to know everything and we can’t. We definitely shouldn’t pretend to. Personally, I like a politician who occasionally says, ‘you know what, I really haven’t a clue.’

• Face up to the fact that there may not be a single objective truth. Fact find by all means but trust your instinct too. Alternative facts are troublesome, but alternative opinions aren’t. If we’d approached Brexit with that in mind, it might have been a different story whatever the outcome.

• Acknowledge that things aren’t always black and white. Favour doubt over certainty, distance over nearness, complexity over simplicity. Nuance is fertile territory in the search for truth. Embrace greyness. Discursiveness may make for frustrating discourse. But sometimes the long way round is a good way.

• Accept too that truth isn’t about one thing. So it’s not about evidence or emotion because they aren’t mutually exclusive. It surely has to be about both and the relationship between them.

• Above all, cherish disagreement as much as agreement. Move out of the echo chambers which are a hostage to distrust. The longer we stay in them the further we get from any shared sense of the truth. We stop being curious. Then compromise, consensus and the like become impossible.

There was something of a call to arms and action at last night’s debate. The idea that we need more public rallies. I’m not sure. They might have a part to play. But although I think they can be better than exchanging arguments in the ether, I think they often just serve to reinforce distrust.

Corbyn’s rally at Glastonbury may be more benign than a Trump rally where everyone cries Drain the swamp, Lock her up and worse. But where’s the exchange of perspectives? Where’s the bit that makes us think?

Adversarial conversations have their place too. But if they are the only show in town, things soon get quite polarised. I can go to a pantomime if I want to but I’d rather our public discourse didn’t resemble the audience’s engagement with the good fairy.

For me the key to all this is dialogue. Talking and listening. In a room. With other people. It’s good to talk. Especially with people you disagree with.

TS Eliot said that ‘Truth on our level is a different thing from truth for the jellyfish.’ But that’s only true if we engage with each other as human beings.