A centralized system is one in which one element or subsystem plays a major or dominant role in the operation of the system. A small change in this subsystem will then be reflected throughout the system, causing considerable change. Progressive centralization is the process whereby one such part of the system emerges as a central and controlling agency. Progressive centralization is especially important in the biological realm where it is associated with progressive individualization (in that an individual can be defined as a centralized system which grows, through progressive centralization, more and more unified and indivisible).
At the higher levels of an organization, centralization is essential to maintain a common pattern of accepted purposes, to coordinate many activities that may otherwise serve to defeat each other, and to provide a general framework for decentralized action. It is needed to prevent or counteract external efforts to weaken or destroy the organization through divisive action, and is needed to deal with external controllers, who may demand it in order to see that control is effective. It should be noted also that a highly centralized system may have several dominant centers. This organization may have redundancy features in order to provide back-up for contingencies. Thus there are two lungs in the human pulmonary system, for example, and the human brain has some redundancy features among its left-right hemisphere divisions, and among the limbic and neo-cortex portions etc. Finally, centralization need not be defined spatially at all, i.e. by where one or a few dominant sub-systems or elements are located. A truly centralized system may be one with a central logic.