 As mentioned above, it is convenient to conceive of social institutions as possessed of three dimensions, namely, structure, function and culture. While the structure, function and culture of an institution provide a framework within which individuals act, they do not fully determine the actions of individuals. There are a number of reasons why this is so. For one thing, rules, norms and ends cannot cover every contingency that might arise; for another, rules, norms and so on, themselves need to be interpreted and applied. Moreover, changing circumstances and unforeseeable problems make it desirable to vest institutional role occupants (individually or jointly) with discretionary powers to rethink and adjust old rules, norms, and ends, and sometimes elaborate new ones (Warwick 1981)