An ideology is a set of beliefs, aims and ideas, especially in politics. An ideology can be thought of as a comprehensive vision, as a way of looking at things (compare Weltanschauung), as in common sense (see Ideology in everyday society below) and several philosophical tendencies (see Political ideologies), or a set of ideas proposed by the dominant class of a society to all members of this society. The main purpose behind an ideology is to offer change in society through a normative thought process. Ideologies are systems of abstract thought (as opposed to mere ideation) applied to public matters and thus make this concept central to politics. Implicitly every political tendency entails an ideology whether or not it is propounded as an explicit system of thought.

(For the Marxist definition of ideology see Ideology as an instrument of social reproduction below.)

Ideology and Semiotic Theory

According to Bob Hodge's article in the Semiotic Encyclopedia Online (http://www.semioticon.com/seo/contents.html), Ideology "identifies a unitary object that incorporates complex sets of meanings with the social agents and processes that produced them. No other term captures this object as well as ‘ideology'. Foucault's ‘episteme' is too narrow and abstract, not social enough. His ‘discourse', popular because it covers some of ‘ideology's' terrain with less baggage, is too confined to verbal systems. ‘Worldview' is too metaphysical, ‘propaganda' too loaded. Despite or because of its contradictions, ‘ideology' still plays a key role in semiotics oriented to social, political life" (http://www.semioticon.com/seo/I/ideology.html#).

A detailed entry can be found at Semiotic Encyclopedia Online. www.semioticon.com

Ideology in Cognitive Science, Linguistics, Philosophy, Post-Modernism and Critical Theory

In public discussions, certain ideas arise more commonly than others. Often people with diverse backgrounds and interests may find themselves thinking alike in startling ways. Social scientists might explain this phenomenon as evidence of ideologies.

Dominant ideologies appear as "neutral", holding to assumptions that are largely unchallenged. Meanwhile, all other ideologies that differ from the dominant ideology are seen as radical, no matter what the content of their actual vision may be. The philosopher Michel Foucault wrote about the concept of apparent ideological neutrality. Ideology is not the same thing as philosophy. Philosophy is a way of living life, while ideology is an almost ideal way of life for society. Some attribute to ideology positive characteristics like vigor and fervor, or negative features like excessive certitude and fundamentalist rigor.

Organizations that strive for power will try to influence the ideology of a society to become closer to what they want it to be. Political organizations (governments included) and other groups (e.g. lobbyists) try to influence people by broadcasting their opinions.