It is commonly held that Marx defined productive labor as labor on the production of material goods. This apparently purely academic proposition has quite far-reaching consequences, one of which is that social production defines, both statistically and in conception, only the material part of production. Services are not included, which means that often no serious social accounting is made of them. In a modern economy, however, the number of those employed in the service sector increases faster than the number of those in the material production sector, so that the standard of living, economic stability, etc., depend to an almost decisive extent on what takes place in productive services. Moreover, the term "productive" has a definite emotional content. It is a good thing to be "productive" and it is embarrassing to be "nonproductive." There will even be political theories about "producers" or "direct producers," who are the bearers of the social system and for that reason are automatically progressive, in contrast to the more or less dubious "nonproducers." 1 All this indicates the great theoretical and practical significance of a correct definition of the concept of productive labor. The word "correct" should not be interpreted as meaning "true," for definitions are inherently neither true nor false, but "useful" or "adequate" with respect to a broad theoretical domain in which 123the concept of productive labor is to have a definite categorical function.