The polarity between social structural theory and economic theory- particularly the distinct positions each takes regarding persistence and change in economic institutions-has been useful theoretically, but it is obvious that an explanation of the real dynamic of economic institutional change lies somewhere between the views proposed by each of these theories. As Granovetter (1981) and Jencks (1981) have noted, advocates of social structural theory concede that social structures must eventually change in response to economic forces just as economists concede the existence of temporary disequilibria and imperfect markets which sometimes make earnings temporarily unresponsive to change. The more important issues here, however, which neither theory adequately addresses, are, according to Granovetter and Jencks, more complex. Rather than investigating whether or not change occurs, the real issues to deal with here are what kinds of forces, over what periods of time, create what kinds of changes in economic and social inequalities.
While sociological models portray organization structures as rigid and unchanging as the buildings in which they are housed, the corporation analyzed in this volume did in fact grow and subsequently contract during the period studied; and this growth and contraction affected the demand for various kinds of employees. Like the Weberian model of bureaucracy, the model of the career selection process presented here presumes distinctive preferences among employee at-tributes. This model also portrays the selection system as a series of selections operating over time, and this sequential nature of the process may make selections susceptible to change from external influences. However, until now, the ways that career structure may be changeable have not been specified.
The present article shifts the focus from specifying how individual careers unfold over time to describing how career trajectories are affected by historical forces. It describes careers by comparing cross-sectional analyses of random samples of employees in four different periods. Although this procedure does not yield quite the same parameters as longitudinal analysis, it does make it possible to investigate how these parameters change over periods of increasing and decreasing growth, contraction, and affirmative action.
Neither economic nor structural theories are entirely satisfactory for predicting outcomes here. While economic theory provides a dynamic mechanism to explain a system's responsiveness to such changing influences, it assumes that the structure is "rational" in the economists' radically individualistic sense of the term. On the other hand, while most structural theories pose explanations for lack of changes, they generally do not pose explanations for changes.
This article presents a dynamic structural model which posits that career selections are the result of tournament processes, and the tournament's selectivity is affected by a dynamic supply-demand mechanism. This dynamic structural model is in many ways similar to economic theory: Increased demand raises attainments and decreased demand lowers attainments. But, unlike economic theory, the dynamic structural model posits that changes in the supply-demand relationship affect the selectivity of the promotion system; and, as a result, some structural limitations are imposed which are not imposed by economic theory. The dynamic structural model proposes two sets of hypotheses to explain these structural limitations.
One set of hypotheses-the developmental hypotheses-describes differential responsiveness as careers progress. They contend that individuals' job status attainments become increasingly enmeshed in the career structure over time, so that careers become increasingly less responsive to external forces as they unfold. The other set of hypotheses-the selectivity hypotheses-describe the differential responsiveness of different employee groups. These hypotheses contend that the balance of supply and demand, rather than affecting all groups equally, has least influence on the highest and lowest status groups. While economic theory provides a parsimonious model of the outcomes in many cases, these hypotheses suggest that the actual selection process is more complex, and the changeability of career trajectories is dependent on employees' career stages and status attributes.
Changes in Career Trajectories: Developmental Hypotheses
The tournament model of careers in many ways resembles the developmental model in biology. Both models posit that development ii patterned by an underlying structure, and both characterize the structure of development quite similarly. Like the developmental model, the tournament model posits that careers advance through stages, and these stages are irreversible. The stages suggested by tin tournament model are similar to those described by the developmental model: Early careers are characterized by rapid advancement and differentiation of a cohort, middle stages are characterized by increasingly slower advancement and differentiation, and later stages by a plateau and perhaps a decline (see Bloom 1964; Kagan 1969; Kohlberg 1969) Like the developmental model, the tournament model suggests thai individuals may advance at different rates and to different final attainments and that rate and final attainment are related: Those who fail tc advance in early career are less likely to continue advancing thereafter The loss of developmental "momentum" is likely to lead to a plateau.
Most important for the present article, both models also contend that development is structured in another sense: It is resistant to change. The developmental theory in biology posits that organisms become increasingly resistant to change over time. According to developmental theory, organisms are responsive to external environmental forces in the early stages of their development when their most rapid changes are taking place; thereafter, as development slows over time, responsiveness also declines. For instance, studies of the relationship of drug consumption during pregnancy and infant malformation conclude that "developing structures are most vulnerable during the period of their most rapid development" (Fein et al., 1983). Similarly, developmental theory also suggests that there are differences among organisms in how responsive they are. It posits that organisms which exhibit more changes in their normal development are also more responsive to external forces than are organisms which change less.
The tournament model suggests analogous predictions for careers. It suggests that careers are most responsive to external forces in their early stages, for that is the period when the tournament system allows many selections to occur and when individuals' career trajectories are still unfrozen. Thereafter, as careers become increasingly well defined and limited and as individuals increasingly receive specialized training, socialization, and an accumulation of signals defining their career futures; the tournament model predicts that careers become less responsive. Similarly, the tournament model specifies that employee groups differ in how much career change they may anticipate in the normal development of their careers; and, following the prediction of developmental theory, it is predicted here that employee groups that normally receive more advancement will be more responsive to external influence than those who normally receive little advancement.
