criminal career research has been criticized for a lack of theoretical foundation (Gottfredson and Hirschi, 1988; for a rebuttal, see Blumstein, Cohen, and Farrington, 1988b). This critique is justified to the extent that the fundamental focus of the research – prevalence, frequency, onset, duration, and desistance – is epidemiological and descriptive, rather than theory-driven. The primary aim is the mapping of variations and patterns in individual career trajectories. Such studies represent a method for disaggregating the criminal career into distinct and measurable components.

Studies of specialization and escalation may also be considered descriptive, but can at the same time be said to concern hypothesis testing. The hypotheses tested, however, tend to originate from common assumptions regarding the development of criminal careers rather than specific criminological theories.

Despite the above, the inductive nature of criminal career research does not exclude the results from being related to criminological theories. Furthermore, the results of criminal career research can be used to support or challenge criminological theories, depending on whether the patterns that emerge are embraced or explicable by common theoretical perspectives. The results may point to the shortcomings of some theories, or raise questions regarding the ability of general theories to explain fully the variation observed in individual offending patterns.

This final chapter reviews the most important findings of the current study, summarizes the material on deterrence and incapacitation, and comments on the implications of this work for criminological theories and criminal justice policy.