The study and practice of criminology delves into crime causation and factors that contribute to offender criminality. This means considering four basic theories: Rational Choice, Sociological Positivism, Biological Positivism and Psychological Positivism. The theories rely on logic to explain why a person commits a crime and whether the criminal act is the result of a rational decision, internal predisposition or external aspects. The law and judicial system is structured around use of these theories.
Rational Cause or "choice theory" developed by 18th century Italian philosopher and politician, Cesare Becarria, is considered the classical school of thought and depicts criminals as deviants. The basis of the theory explains offender motivation to commit a crime as a purposeful decision with intent of personal gain in the form of ego-boosting incentives such as money, power, status or learning. Rational cause theory purports that the offender makes a choice to commit a criminal act upon examining options, consequences and benefits. The offender then plans the crime by consciously picking the type of crime, location of the crime and target of the crime, and executes the crime with awareness that it is wrong and control to choose otherwise.
Sociological Positivism, popularized by statisticians Lambert Adolphe Jacques Quetelet and André-Michel Guerry in the 1800s, examines relationships between societal influences and crime. Sociological theory is driven by a study of social structures within an offender's environment such as family, peer groups, socioeconomic status, education level and subculture that led to his criminality. The theory focuses on how an offender conforms to his surroundings, becoming a product of his environment and social learning. This concept proposes that criminality is inevitable under circumstances such as ongoing exposure to social disorganization in a criminal culture, stigmatization, strain including poverty, a break-down in family or moral values and family or community-justified crime.
Biological Positivism, theorized by Italian criminologist Cesare Lombroso in the late 1800s, is based in anthropology, and studies the evolution and physiological differences between criminals and non-criminals, theorizing that some people are born-criminals. The belief is that criminals are predisposed to commit crime as a result of biological inferiority versus personal choice. This theory takes an objective and scientific approach to understanding crime by researching an array of physiological factors that may contribute to criminality such as vitamin deficiencies, hormonal imbalances, diet and brain function.
Psychological Positivism, theorized by French criminologist Alexander Lacassagne in the 1800s, proposes that the causation of criminality is rooted in offender mental illness or personality disorders. Examples include schizophrenia, bi-polar disorder, psychopathic personality, antisocial personality disorder, depression and neuroticism. Disorders may be the result of sociological or biological factors such as physical or sexual abuse, parental criminology and intelligence level. Psychological Positivism analyzes criminality as the result of an internal and unavoidable cause versus that of a controlled decision.