It seems that common sense is established in response to norms, practices, etiquette and morals formed by a certain culture or subculture. Sober explains that testing certain philosophical theories such as egoism is problematic because they (like the concept of common sense) require background assumptions that are not always present or consistent. If specific background frameworks are set, one may avoid fallacies in defending or attacking a theory, but the theories themselves are still not fundamentally established.