The problem with Nazi ideology and the Communist state, with bureaucracies and corporations, comes down to a problem of discourse. Discourse is communication of all sorts. Critical theory holds that our rational structures of organization in society undermine the possibility of true discourse in various ways. The goal of critical theory is to make real communication possible. This is communication in which people are not regarded as just part of a public or a market, are not simply the result of rationalized bureaucracies, nor part of some political ideology. This is communication which does not disguise itself as voting or shopping, opinion polls or propaganda.
The goal of much critical theory is to understand discourse in all its forms, and particularly to show how seemingly free and equal discourse is in fact laden with assumptions, and privileges the interests of a few.