Bill Clinton has warned that the Brexit vote was about people thinking differences are more important that what they have in common.
The former US president also suggested that some people who backed the split from the EU last year were not fully aware of what they had voted for.
After being honoured by Dublin City University for his work on peace and reconciliation in Northern Ireland, Mr Clinton said he used the example of the Good Friday Agreement shamelessly around the world.
The accord was signed in 1998, mid-way through his two terms in the White House, after he took a more hands-on approach to US diplomacy at the height of the Troubles.
Mr Clinton warned about inequalities and divisions spreading around the world.
“Now there are lots of people who think they are less human,” he said.
“Now given the economic inequalities and the rapid pace of social change and all the upheaveal that’s going on …. people are reassessing whether what we have in common is more important than our differences.”
“A lot of people begged to differ.”
“That’s really what the Brexit vote is all about.”
Mr Clinton, who was given an honorary doctorate in DCU, the highest award the college bestows, suggested that some Brexit voters may only be realising the impact of the loss of access to the EU Customs.
Mimicking a voter, he added: “I’m sorry we can’t stay together, we had a disagreement. Oh my God, I didn’t know I was going to lose that customs thing and all these econ benefits. Why didn’t anyone tell me that?”
Mr Clinton added: “All partnerships that are community-based are held together not because everybody agrees with everybody else, not because we don’t still have our particular identities, but because co-operation is better than conflict or isolation in any environment in which you must be in touch with others.”
“It’s a simple proposition. But we are re-litigating it now.”
Mr Clinton said this happened in the Brexit vote but also in elections in France, Germany, the Netherlands and Austria.
“In every place there was a nationalist party that said the other is dragging us down. We can’t accommodate all this diversity,” he said.
“The world is now in a conflict whether we should stop our mingling with others at the tribal level or whether communities are better; whether diverse groups make better decisions and create wealth and life and opportunity or homogenous ones do as they don’t push us so hard and we feel more secure.”
“We can’t get away from each other so we should look at our neighbours without regard to their race, religion, their orientation or whatever.”