In the late 1840s, a man named Owen Finnegan left Ireland to settle in New York. Little did he know that one day his great-great-grandson would return as president of his adopted nation.

Later today, Joe BidenThe president of the USA, elected in 2020. will arrive in BelfastThe capital of Northern Ireland. to mark the 25th anniversary of the Good Friday AgreementThe treaty that ended the Troubles, a decades-long conflict between Catholics and Protestants in Northern Ireland, which also saw fighting between the British government and Irish republicans. One of its central tenets is an open border between Northern Ireland and the Republic of Ireland. (GFA), a peace deal that brought to an end 30 years of armed conflict between republicansPeople who believe a country should not have a king or queen, or in the US, members of the Republican party. who wanted a united Ireland, and loyalistsLoyalists believe Northern Ireland should remain a part of the UK and are usually Protestants. who wanted to keep Northern Ireland in the UK.

The deal is still hailed as a great achievement. But for many, the anniversary of this momentous agreement is also a time to reflect on what has not changed.

Under the GFA, the paramilitaryAn unofficial group organised like a military force. forces that plagued Northern Ireland were supposed to disband. But according to experts, loyalist groups have simply shifted their focus towards organised crime.

On the republican side, some IRAThe Irish Republican Army, or IRA, was an unofficial military organization made up of people who wanted an end to British rule in Northern Ireland. splinter groups never accepted the GFA, and continue to fight.

For some, it raises an uncomfortable question: did the deal really bring about peace?

Peace is an elusive thing. Between 1946 and 2005 only 39 of 288 conflicts, 13.5%, ended with a peace deal.¹

One problem is that countries often have no reason to negotiate. If one side believes it is winning the war, it will usually prefer to keep fighting. So both sides have to feel they have more to gain from peace.

And the leaders who make peace then have to persuade their peoples to abide by the agreement. Often they are traumatised and angry. They might respond by removing their leaders and installing more radical ones who want to renew the conflict.

Moreover, political leaders often do not participate in peace deals in good faith. They can be used as a PRPublic Relations - the practice of managing how others see a brand or person. move, or to gain a military advantage. That makes it difficult to rebuild trust for a new round of negotiations.

Yes: The vast majority of conflicts do not end in a peace deal. In most cases, one side simply crushes the other. Or there is a cycle of violence as ceasefireAn end to fighting - often temporary. after ceasefire is broken.

No: Coming to an agreement can be difficult, but peace usually reigns in the end. People get exhausted by fighting. In the end, all they want is stability and an end to the chaos.

Or... Peace is easy; justice is hard. For a peace to last it must be based on a sense among the people affected that justice has been served. Otherwise they are certain to take up arms again.