The assumption of Ehrlich's research hypothesis is that human beings, including offenders, seek to maximize the personal benefits gained from behavior, which means avoiding behavior deemed likely to bring personal harm. This translates into Ehrlich's prediction that increasing the probability of apprehension and the severity of punishment will significantly deter criminal behavior. Capital punishment is included as one of the battery of punishments measured. Ehrlich's findings from the empirical data support the hypotheses. Beyleveld criticizes the accuracy of Ehrlich's hypotheses apart from their fit with the empirical data. The hypotheses, however, can only be rendered valid or invalid on the basis of their power to explain the empirical data. Beyleveld further argues that the hypotheses prejudge what the empirical data will show and that alternative hypotheses for explaining the data were not considered. The hypotheses, however, cannot force the data to support them, and Ehrlich did consider reasonable alternative explanations of his findings. Further, Beyleveld argues that Ehrlich has not considered the ethical implications of his conclusion that capital punishment deters homicides. Ehrlich answers that his conclusions are scientific findings and that it is up to policymakers to wrestle with their ethical implications. Twenty-three references are listed.