further categorized as "habitual criminals", who become so by contact with other criminals, the abuse of alcohol, or other "distressing circumstances." This category included "juridical criminals", who fall afoul of the law by accident; and the "criminal by passion", hot-headed and impulsive persons who commit violent acts when provoked. Ferri's penology Ferri was instrumental in formulating the concept of "social defense" as a justification for punishment. This theory of punishment asserts that its purpose is not to deter or to rehabilitate, for how could behavior not based on rational calculus be deterred, and how could born criminals be rehabilitated? Given the assumptions of biological positivism, the only reasonable rationale for punishing offenders is to incapacitate them for as long as possible so that they no longer posed a threat to the peace and security of society. This theory of punishment provides us with an example of how anthropological assumptions drive policies for dealing with crime and criminals. He was, however, an ardent proponent of measures to prevent crime among "occasional criminals" through social reform, and of efforts to rehabilitate them. Garofalo's "natural" definition of crime Garofalo is perhaps best known for his efforts to formulate a "natural" definition of crime. Classical thinkers accepted the legal definition of crime uncritically; crime is what the law says it is. This appeared to be rather arbitrary and "unscientific" to Garofalo (like the British-American system of linear measurement) who wanted to anchor the definition of crime in something natural (like tying linear measurement to the circumference of the earth, as in the metric system). Garofalo felt that definitions of crime should be anchored in human nature, by which he meant that a given act would be considered a crime if it were universally condemned, and it would be universally condemned if it offended the natural altruistic sentiments of probity (integrity, honesty) and pity (compassion, sympathy). Natural crimes are evil in themselves (mala in se), whereas other kinds of crimes (mala prohibita) are wrong only because they have been defined as such by the law. Garofalo rejected the classical principle that punishment should fit the crime, arguing instead that it should fit the criminal. As a good positivist, he believed that criminals have little control over their actions. This repudiation of free will (and, therefore, of moral responsibility) and fitting the punishment to the offender would eventually lead to sentencing aimed at the humane and