The democratic peace theory, stating that democracies do not wage war among themselves, is one of the main arguments in favor of the international promotion of democratic governance. It has been around since Immanuel Kant who, in his essay Perpetual Peace, postulated that constitutional republics, or what we now would call democracies, was one of the necessary conditions for a perpetual peace. Recently, this theory has been abused by the US government in order to justify a war against a non-democracy – Iraq – in order to bring lasting peace to the world, but this abuse has not diminished the strength of the argument.
Democracies do not wage war among themselves mainly for the following reasons:
- Democracies are able to make and keep international agreements and to create mechanisms which make it possible to solve international conflicts in a peaceful way. Publicity, as we find it in a democracy, tends to enhance respect for agreements because it makes it harder to cover up violations of agreements. A mentality of respect for the law, which is typical of a democracy because the rule of law is typical of a democracy, promotes respect for international agreements.
- Democracies are able to avoid civil strife because they have judicial systems for solving conflicts between persons or between groups. Civil strife often spills over to other countries and can cause international conflicts (international violence is often the consequence of internal violence). Therefore, avoiding civil strife means avoiding international conflicts. Tolerance, respect, religious freedom and non-discrimination, as guaranteed by human rights and democracy, also protect civil peace and therefore international peace.
- Democracy promotes peace because it provides mechanisms for the peaceful transition from one ruler to another. There is no need for a violent succession struggle which can have international consequences. Opposition movements do not have to resort to extreme tactics in order to prove their point or to take over power. Leaders do not need to engage in dangerous international adventures in order to increase their legitimacy etc.
- Governments which treat their own people with tolerance and respect tend to treat their neighbors in the same way.
- Governments which cannot force people to do something against their will, will find it much harder to go to war. The people most often do not want to go to war, because it is they who suffer in the first place. To some extent, a tyranny does not need the agreement of the people to start or continue a war.