Legalism was one of the four main philosophies in Chinese history during the Warring States Period. It is a political philosophy which says that people are bad by nature and need to be controlled by the government. It was introduced by Qin Shi Huang.
One of the most important contributors to Legalism was Han Fei Zi (韓非子). He said that a ruler must use following tools to govern a state:
1. Fa (Chinese: 法; pinyin: fǎ; literally "law or principle"): The law must be known by everyone. Everybody under the ruler is equal before the law. If you do what law wants you will be rewarded. If you break the law or try to break it, you will be punished.
2. Shu (Chinese: 術; pinyin: shù; literally "method, tactic or art"): These are methods the ruler has to use so that nobody is able to abolish the system.
3. Shi (Chinese: 勢; pinyin: shì; literally "legitimacy, power or charisma"): The position of the ruler is important, not the ruler himself.