Substantially, these postulates hold first, that standardized
social activities or cultural items are functional for the entire social
or cultural system; second, that all such social and cultural items fulfill
sociological functions; and third, that these items are consequently indispensable.
Although these three articles of faith are ordinarily seen only in one
another's company, they had best be examined separately, since each gives
rise to its own distinctive difficulties (1968, p. 79).