Inherent from the contradictions in capitalism is the denial of certain human rights to some groups of society, notably the right to education, work, social security and national self-determination. This denial may be active or passive. Other rights such as freedom of thought, expression and movement and the right of privacy may also be abrogated. Human rights may be denied on a national or international basis; the latter particularly takes the form of colonialism, economic imperialism, foreign control and intervention. Poverty and alienation are heightened, causing conflict and eventual revolution, which under colonial conditions may take the form of guerrilla warfare and terrorism.