As early as the 18th century, criminologists such as Bentham and Beccaria argued that humans are basically motivated by the desire to maximize pleasure while avoiding pain. They accordingly called for criminal penalties which were definite, invariable, and uniform in application. Such a conception of human behavior and of the utility of punishment as a means of affecting behavior was abandoned under the 20th century view that behavior develops in response to socioeconomic conditions, and that criminal behavior is derived from emotional and economic deprivation. The outgrowth of this perspective was the indeterminate sentence which provided the framework for a rehabilitative approach to corrections, in which release was determined by the offender's manifestations of attitudinal and behavioral change. While such a system tended to motivate the offender to appear contrite and rehabilitated in order to gain release, there was little motivation for actual change. From the offender's perspective, the criminal justice system has become more of an inconvenience that can be easily manipulated for the offender's benefit than a painful experience that should be rationally avoided at all costs. Experience indicates that many if not most offenders are rational to the extent that they act to maximize pleasure and limit pain. Crime has been found to provide a great deal of pleasure, while the criminal justice system provides very little pain to counter the pleasure. What is needed is a determinate sentence structure that guarantees certain consequences for the commission of particular offenses, regardless of apparent rehabilitative progress.