Why wars happen

What is extremely important is culture; in certain cultures at certain times and certain places, fighting war has been acceptable. Governments have thought that war is a useful tool that can be used to achieve its ends, and sometimes war has been a useful tool. However, we have also had cultures – we can still see some of them today – in which those who fight are revered, in which military virtues are revered, in which being brave, being prepared to die and to suffer are viewed as virtuous, particularly for men.

Military virtues are very gendered. Throughout history, men have been expected, and are still expected, to be brave and prepared to fight, and I think that’s cultural. There may be a biological element, but the culture is far more important. It’s a culture that brings young men up to see themselves as people who ought to be warriors and, conversely, brings young women up to see themselves as people who should support the warriors, but not be warriors themselves.

Why countries go to war is a different matter. Even in democratic, peaceful societies, there will be times when people who don't come out of militaristic cultures, who haven't been brought up in this way, will feel that they have to fight. There are several reasons why people fight, but cultural values compel people to fight without even a war taking place.

Steven Pinker and others argue that many societies in the West are becoming much less prone to violence. He points to evidence, for example, that we no longer tolerate public cruelties, such as public executions. In fact, executions have themselves been abolished or are rarely used in many countries, and we no longer tolerate things like public violence and confrontations. However, this is not war. I think we have societies in which peaceful values are paramount, but that still doesn't mean that those societies couldn't go to war if they feel threatened or if they feel that they have a cause.

Often, people will surprise themselves. Americans didn't think they were going to go to war when the war started in Europe in 1939. A lot of Americans considered staying out of that war to be very important – the isolationist sentiment was quite strong in the United States – but that changed almost overnight when the Japanese attacked the Americans at Pearl Harbor. Suddenly, the Americans were enraged. They were furious. People lined up to join the military. Therefore, it really depends on the circumstances.

A lot of the British didn't want to fight a war again for very understandable reasons, nor did the French in the 1920s and 1930s. However, when they felt they were going to be attacked and had no alternative, they did support the war. Accordingly, the support societies will give to war depends partly on cultural values, but also partly on the circumstances. If you feel you have no choice but to fight, or if you feel you've been attacked or threatened, then you may well change your views on whether war is desirable.

I see three main types of reasons. They fight because they want something; they are greedy for slaves, land and loot. There have been opportunistic wars made to take something that someone else has. Saddam Hussein attacked Kuwait at the beginning of the 1990s because he wanted its oil and its wealth. That was a very opportunistic war. He thought he'd get away with it, and cheaply.

People also fight because they're afraid. They feel that they are going to be destroyed and that they have little alternative. The Finns took on the Soviet Union in the Winter War of 1939-1940, even though they were tiny compared to the Soviet Union. They felt they had no alternative, and managed to push the Soviet Union back and to cause enough damage that the Soviet Union came to an understanding with them.

The final reason that individuals, countries, or groups will fight is for ideology, for a cause. The cause can be religious. For instance, Europe had religious wars in the 16th and 17th centuries, and people were prepared to die in the name of their religion and the belief, often, that they would have an afterlife. We've seen religious wars since the end of the Cold War. We've seen people in ISIS or Daesh, for example, motivated by religion. Ideologies such as Bolshevism or nationalism can also be every bit as powerful in motivating countries and groups of people to fight.

The rising tension between the United States and China is very worrying. I don't think either side wants war, but both are making preparations. If you want peace, as was once famously said, prepare for war. However, the danger in preparing for war is that you begin to amass all these weapons, and pressure builds to use them before they become obsolete. When you get into a tense situation with another country or another group of people, you begin to misread them. You begin to look at everything they do as a signal that they are out to get you or that they're planning something. There are these sore points in the world, and I think we need to think of ways in which we can reinforce the forces of peace, international organisations, and get powers to communicate with each other rather than getting into adversarial positions.

I think any international organisation is only as good as its members, and when you have members who don't support it or aim to use it for their own ends, then, of course, it gets weakened. The United Nations has suffered from this and, particularly recently, the Trump administration and the United States has made it very clear that it doesn’t prioritise international organisations. It doesn't believe in supporting them. It doesn't see their point. The gesture of withdrawing from the World Health Organization at a time when it’s clear that you need international cooperation to deal with a global pandemic seems very misguided. It weakens the whole range of international organisations. I think that's worrying.

The United Nations may be unsuccessful in some areas. People tend to hold it up as something that has been a disappointment, but it has played an instrumental role. One of its useful roles is that it provides a forum where the nations of the world can get together, talk to each other, and where – often behind the scenes – they can come to some sort of understanding. There's no other body in the world that does that where virtually every nation in the world is a member. The United Nations has also been useful in coming in after wars are over and trying to deal with post-conflict societies. This is something we need to think about because if you don't end a war successfully and remove the causes of conflict, or at least begin to rebuild societies, then you simply leave the door open for more wars to take place. It’s crucial to keep reminding ourselves and the next generations that these organisations are not just remnants of the past, they are essential in trying to keep a peaceful world.

Societies have often used war and military triumphs as ways of bringing themselves together and ways of commemorating great moments in the past. My own feeling is that we should not be looking at war in the past as a way of strengthening our national identity, instead what we should be doing is looking at war as something that we got involved in that we regret. Still, we should also be looking at war as something that crosses borders. We should be thinking about those we fought.

One of the very positive things that has happened in the last few years is that former enemies have come together to commemorate wars in which they fought against each other. The French and the Germans have worked together to create a museum, for example, to commemorate the First World War. They have come together at commemoration services for the First World War and also for the Second World War, and I think this is important. The glorification of war is dangerous. We are more than our past triumphs, and we need to remember that.