As a formal analytical point of reference, primacy of orientation to the attainment of a specific goal is used as the defining characteristic of an o… - Talcott Parsons

Ideology is a system of beliefs, held in common by the members of a collectivity.

A social system consists in a plurality of individual actors interacting with each other in a situation which has at least a physical or environmental aspect, actors who are motivated in terms of a tendency to the "optimization of gratification" and whose relation to their situations, including each other, is defined and mediated in terms of a system of culturally structured and shared symbols.

'System' is the concept that refers both to a complex of interdependencies between parts, components, and processes, that involves discernible regularities of relationships, and to a similar type of interdependency between such a complex and its surrounding environment.