The influence of the middle class depends on which theory one utilizes. If the middle class is defined as a modern bourgeoisie, the "middle class" has great influence. If middle class is used in a manner that includes all persons who are at neither extreme of the social strata, it might still be influential, as such definition may include the "professional middle class", which is then commonly referred to as the "upper middle class". Despite the fact that the professional (upper) middle class is a privileged minority, it is the perhaps the most influential class in the United States.