Interests are different from mere opinions. Interest refers to far stronger convictions, rooted most often in rational selfishness but often extended outside the economic realm to include belief systems up to the symbolic if strongly felt.

The vertical axis is concerned with the degree to which interest are autonomous or are shared. Interests are thought to arise out of the condition of an individual's life. This was indeed the first outright recognition of the dignity of interest in political as well as economic thought, originating largely with Locke. It was only with mid nineteenth century, with Marxist theorizing and socialist ideology, that interest came to be interpreted as an offshoot of the aggregate dimension, with class becoming the modern catchword for social - and conflicting - interests. The horizontal axis incorporates the variety of means by which interests are accomodated and aggregated in the modern polity. The basic distinction refers here to procedural versus substantive mechanisms or processes to put interests forward.