What it is: In politics, this is the theory that the best way to keep order internationally is to make sure that no single state (or alliance of states) becomes more powerful than the rest.

What it means: People have believed in this theory for many centuries. They have sometimes even applied it to the way individual people jockey for power, whether in a family, at school/college, or at work. Internationally, seeking a 'balance of power' has been used to justify increasing a state's military power, rather than the opposite. 'Balance of power' also refers to the way power is distributed, which can be very complicated when more than two or three states are involved. After the development of nuclear weapons began, some people began to refer to a 'balance of terror' as well.

Think about it: 'Balancing' is by definition a precarious business, implying a continual struggle for stability, which will only end when it is given up altogether. An apparently stable relationship can be knocked off balance in a moment, sometimes by something apparently quite trivial. So if relationships between people or countries are based on power, rather than friendship, trouble is always likely. Can there be real 'order' and peace as long as it's power that someone or some country wants, and wants to keep when they've got it? How might people and states live, work and interact together without the risk of disastrous disagreements and disputes?