a) All knowledge is Ideology. Foucault equates all knowledge as power; words inherently not only describe but regulate the control (definition and flow of) meaning. Examples “CIVILIZATION”. White/Black. 

 

Foucault views Ideology much as Marxism does, but he:

 

b) Shifted attention from economic relations to include all relationships between people.

 

c) Shifted attention from the Marxist focus on economics/means of production to power, in more general, universal terms. 

 

In terms of philosophy, he shifted the role of philosophy from understanding the nature of “truth” to the “historical production of what is considered to be true” -- in other words, he is interested in charting the history of how different institutions have gone about producing ideas (Ideology) that then general becomes accepted as "true", and what contexts and other historical and sociological etc. forces influence that process.

 

“Foucault's ideas of power/knowledge bring to our attention the fact that in fields of specialized knowledge, our actions are governed by the constituents of the power structures themselves. What does this mean? This means that there cannot be criminology without prisons, forensic DNA without police, and medicine without the clinic. It means the understanding in fields of knowledge are manufactured within their discourses.

… In addition, power is not possible without the knowledge.

Therefore, we can only have "knowledge" of psychiatry with the dichotomous conditions such a discourse will bring forward. Having a specialist knowledge in a unique discourse allows a psychiatrist to have unique power and control. The psychiatrist has power to diagnose a condition, and because the person belongs to this specialist discourse, their word is considered authoritative and "true." Hence, they have power.”
http://www.colostate.edu/Depts/Speech/rccs/theory54.htm