Democratic Peace Theory

Do democracies go to war with each other? Understanding the Democratic Peace Theory

One of the most talked-about ideas in political science is the belief that democracies don’t go to war with one another. This idea is called the Democratic Peace Theory. At its core, the theory says that while democracies may go to war with non-democracies, they almost never fight wars against each other. In fact, many supporters of the theory argue that there has never been a full-scale war between two well-established democracies in modern history.

Where did the theory come from?

The roots of the idea go back hundreds of years. In the late 1700s, the German philosopher Immanuel Kant wrote about the possibility of “perpetual peace” in a world where all nations were republics - that is, countries where leaders are elected and people have a say in government. Kant believed that when citizens have the power to decide whether their country goes to war, they’ll think twice about it, because they are the ones who will suffer the consequences.

But the modern version of Democratic Peace Theory didn’t fully develop until the 20th century. Political scientists like Michael Doyle, Bruce Russett, and R. J. Rummel were key figures in researching and promoting the theory. They studied hundreds of wars and found a surprising pattern: wars between democratic nations were either extremely rare or didn’t happen at all.



What is a democracy?

To understand the theory, we have to be clear about what a democracy is. Now, a democracy, in its original, purest sense of the word, would mean that all citizens who are eligible to vote would have a direct say on all matters and decisions. Think ancient Greece. This is actually not the case for us in the United States and other countries we call democracies. The U.S. and these other countries who are called democracies are actually republics, the form of government Immanuel Kant wrote about, as previously stated. In a republic, citizens who are eligible to vote elect representatives, who then, in turn, make decisions and operate the day-to-day business of government on behalf of the citizenry. For whatever reasons, the terms democracy and republic in modern times have often become intertwined and hence used interchangeably by many. For the sake of simplicity, though, a democracy, for purposes of this discussion, is a political system where:

• Leaders are elected by the people.
• Citizens have basic rights, like freedom of speech, freedom of the press, and freedom of religion.
• There are regular, fair elections.
• The rule of law is respected - meaning no one is above the law.

Not every country that calls itself a democracy (or a republic, for that matter) meets all these standards, however. As just a few examples, the full name of North Korea is the Democratic People's Republic of Korea. China's full name is the People's Republic of China. Vietnam's full name is the Socialist Republic of Vietnam. The former Soviet Union's full name was the Union of Soviet Socialist Republics (italics are my emphasis). The theory usually only applies to mature, liberal democracies, not countries that may hold elections but offer no real freedom, like the basic freedoms mentioned above.

Why might democracies avoid war with each other?

Supporters of Democratic Peace Theory give a few reasons for why democracies don’t fight each other:

• Shared norms and values - Democracies are used to solving problems through discussion and compromise. They tend to treat other democracies the same way. If both sides believe in talking things out rather than using force, war becomes less likely.
• Political pressure from citizens - In a democracy, leaders have to answer to the people. War is dangerous, expensive, and unpopular. Citizens can vote leaders out of office if they start a war without good reason. This makes democratic leaders more cautious.
• Transparency and trust - Democracies usually have open governments. They debate foreign policy in public. This makes it easier for other democratic countries to trust them and harder for leaders to lie about their actions.
• Economic ties - Democracies often trade a lot with each other. War would ruin these economic benefits. It’s in both countries’ interests to stay peaceful.

Are there exceptions?

Critics of the theory point out that democracies have been involved in many wars - just usually not against each other. For example, the United States has fought wars in Vietnam, Iraq, and Afghanistan. But those were not against other democracies. Critics also argue that the theory depends too much on how we define “democracy” and “war.” If we stretch or shrink those definitions, we can make the theory seem more true or less true.

There have been a few close calls. For example, during the Kargil War in 1999, India and Pakistan - both with elected governments - fought a brief conflict. Some argue this challenges the theory. But others say Pakistan wasn’t a true democracy at the time because the military still had a lot of control. UPDATE: In early May 2025, India fired missiles on Pakistan after Indian tourists in India-controlled Kashmir were massacred by militants the month before, in April 2025.



Why does it matter?

The Democratic Peace Theory gives us a reason to promote democracy around the world. If the theory holds true, then spreading democracy could lead to a more peaceful world. It also affects how countries build alliances, plan foreign policy, and think about global conflict.

But it's important to remember that the theory doesn’t say democracies are peaceful in general - just that they are peaceful with each other. A democracy can still go to war. But if more of the world becomes democratic, and if the theory holds, then wars might become less common.

Conclusion

The Democratic Peace Theory is a powerful idea in political science. It’s based on the observation that democracies almost never go to war with each other. Philosophers like Immanuel Kant and modern scholars like Michael Doyle helped shape this theory. While there are debates and exceptions, the theory continues to influence how people think about peace, conflict, and the spread of democracy. Whether it’s a perfect explanation or just one piece of a larger puzzle, it gives us hope that more democratic nations might mean fewer wars.