One common meaning of the term is "false consciousness," i.e. a system of ideas that is a problem because it presents a false picture of the world (and often, it is assumed, is maliciously propagated, i.e., propaganda). For example, for several decades, the US supported undemocratic right-wing governments like Kuwait's and Guatemala's dictatorships, but was hostile to relatively democratic left-wing governments like that of Chile's Salvador Allende. Noam Chomsky and Edward Herman explain this pattern as the result of systematic distortion or lying on the part of the mainstream media coupled to "the ideology of anticommunism." People were mislead by the falsehoods in the media; if the media had been more truthful, the argument goes, Americans would not have tolerated such an unjust policy.

In the cases they discuss, Chomsky and Herman make many important points. The media do at times lie and distort, and this does have an effect on people's beliefs. But there can be problems with this line of reasoning. On the one hand, it's not entirely clear that if people were exposed to the "truth" they would invariably adopt enlightened views. There are cases where the media provides quite a variety of viewpoints and yet many people's views are troubling; American commercial television tends to support racial integration, for example, yet a great number of Americans seem lukewarm to the idea. On the other hand, since in the US alternative views are available in places like the alternative media, the implication is that common people are too preoccupied to do their own investigating and make their own reasonable judgments about events. At its worst the implication of this line of reasoning is that ordinary people (unlike left media critics) are simply too stupid or lazy to uncover the clear truth of the matter: common people are dopes. For anyone committed to democracy, this is not a very good starting point from which to win large numbers of converts.

Semiotics is often associated with a broad range of thinking that characterizes "ideology" differently. Ideology, many have argued, is best understood, not as false consciousness, but as something embedded in a culture's "common sense," in the everyday habits of thought that shape how we think and act as we go about our day-to-day, routine activities. Ideology in this second sense is not a manipulation of consciousness, but it thrives beneath consciousness, in the taken-for-granted; it doesn't pull the wool over our eyes, but it brings us to take some things for granted, as so obvious that we need not reflect on them.

In this second sense of "ideology," the key questions are not ones of truth or falsehood; because everyone takes certain parts of their life for granted, there's no such thing as non-ideological consciousness. Hence, the only honest way to use the word ideology, to study and unmask ideology, is if one includes one's own ideologies in the process; besides trying to figure out others' ideologies, we all need to continuously ask ourselves about our own "common sense." The analysis of ideology then becomes a continuous process of asking questions about the common sense assumptions, the taken-for-granted background, of both others and our own everyday thought.