Political Stability and Instability
Political leaders, movements, parties, governments do not last forever, but must change and adapt in response to changing conditions. Political change can be quiet and uneventful, as when power is peacefully transferred from one party to another after an election. Large-scale changes in the basic form of government are sometimes more tumultuous, even violent. Revolutions, which topple governments and impose sweeping change, are comparatively rare in history.
As Thomas Jefferson observed in the Declaration of Independence, citizens do not rebel unless they find their government unbearable: "experience hath shown that mankind are more disposed to suffer, while evils are sufferable, than to right themselves by abolishing the forms to which they are accustomed." On the other hand, Jefferson believed that citizens were entitled to rebel against their government if it failed to protect their liberties, and even believed that occasional rebellions were virtually necessary in order to ensure citizens' freedom. Jefferson, as well as some French revolutionaries, justified rebellion with the maxim that "The tree of liberty must be watered periodically with the blood of tyrants."