The Old Testament records that Cain, the first-born son of Adam and Eve, murdered his younger brother Abel in cold blood. (1) As a consequence of this sin, God cursed Cain to live as a "fugitive and a vagabond" forever after. (2) Cain responded to his plight by crying "every one that findeth me shall slay me." (3) The Lord thus proclaimed that "whosoever slayeth Cain, vengeance shall be taken on him sevenfold." (4) God subsequently set a mark upon Cain, "lest any finding him should kill him." (5) Behavioral psychologists have long sought to pinpoint a similar sort of "mark" in modern day criminals--namely, a genetic or other biological marker that could serve to identify those who may have a propensity to commit violent criminal acts.
Efforts to establish a link between criminal behavior and biological or environmental "causes" are nothing new. Cesare Lombroso, the nineteenth century Italian criminologist, was perhaps the first to argue on an allegedly scientific basis that criminals are born, not made. (6) He drew on the emerging theories of evolution and genetics--as well as the pseudo-science of phrenology--to proclaim that individuals possessing a "criminal mind" might be identified by certain peculiar deformations of their skulls. Although Lombroso's theories did not withstand the test of rigorous analysis, psychiatrists (among others) are revisiting the possibility that certain criminal behaviors may possess a biological origin.
While sociologists have long advanced environmental and other sociological theories (poor nutrition, poverty, racism, etc.) under the rubric of "root causes of crime" to explain criminal behavior, (7) efforts to identify biological causes for explaining this same conduct have long been viewed as taboo. (8) One's environment, or so it has been perceived, is inherently manipulable, thus an individual's circumstances may be altered to effect a change in the individual's behavior. Identification of an environmental "cause" influencing behavior thus does not challenge prevailing orthodoxies that view man largely as a product of external forces. The concern is that biology, unlike environment, is not quite as easily manipulable (although that notion is itself coming under scrutiny) and thus places the individual at the mercy of her genes. As a result, critics of biological research into human behavior have regarded as suspect any claim that biology forms the basis for behavior.
Nevertheless, with the rise of evolutionary psychology, biological psychiatry, and more sophisticated tools for understanding and mapping basic brain activity, biological theories of human behavior--particularly violent, impulsive conduct--are resurfacing. (9) It is hardly news that the brain has something to do with the way we think and act. Only recently, however, have researchers begun to identify and to understand certain neurochemical and neurophysiological correlates of mentation and behavior. (10) The resulting body of knowledge, though in its own right profound, is nevertheless still far from answering many fundamental questions about the causes of criminal behavior or from providing us with a reliable mark of Cain to ferret out those likely to engage in criminal conduct. The prospect that such findings may be in the offing, however, requires us to grapple with some of the most fundamental principles by which we assess--and ultimately criminalize--certain types of behavior.
In this essay, I hope briefly to raise several of the more fundamental issues raised by this burgeoning understanding of the mechanisms influencing human behavior--specifically, questions surrounding the meaning of criminal intent and the moral justification for imposing punishment. If, for example, we are better able to understand the biological causes for certain types of behavior, will we be forced to modify ideas of freedom and responsibility because the principal functions these notions serve no longer accurately reflect our understanding of human behavior in light of our discovery of the biological antecedents of decision making? …