Ideology is one of the most difficult and complex concepts in political science and philosophy. Difficulties arise because the term 'ideology' has a series of related yet separate meanings. Most notably it can be used as either a pejorative and critical term or as a neutral, technical one. Confusion often arises because the word can be used in these two senses by the same author, even in the same text or passage. There is also a distinction to be made between the popular usage of the term and its usage in academic and technical writings. In popular usage an ideology is a body of abstract political beliefs which are adhered to even in the face of contrary evidence. A holder of an ideology, an ideologue, is a person so committed to certain theoretical beliefs as to be beyond the reach of common sense and reason. This use of the term is common in Anglo-Saxon countries, although it originated in France. In academic argument, 'ideology' loosely defined means a complex system of attitudes, ideas, and beliefs which gives, or purports to give, a comprehensive account and explanation of the human and natural world. In its most vague and imprecise formulations this comes close to the more general concept of Weltanschauung or world picture, i.e. the general concept or notion of the nature and form of the world which cultures, societies, or even individuals may have as part of their mental furniture. Properly used, ideology should refer to more abstract and complex systems of ideas. The pejorative usage of ideology derives from the thesis that most systematic theories and explanations of the world are not truly objective but rather articulate the interests of a particular class or group and serve to obscure reality rather than to explain it. Ideology in this sense is a type of obfuscation or mystification.