Timothy C. Barnum

1 INTRODUCTION Principles of crime decision-making trace to the Enlightenment philosophers, Beccaria (1963 [1764]) and Bentham (1948 [1789]), and thereafter to foundational work by criminologists such as Gibbs (1968), Tittle (1969), and Chiricos and Waldo (1970), who examined how the certainty and severity of imprisonment influenced crime rates.

Authors are listed in alphabetical order. Additional supporting information can be found online in the Supporting Information section at the end of this article. T. C., Herman, S., Nagin, D. S., & Pickett, J. T. (2026). Understanding bystander decision-making: Experimental evidence on when and how people respond to crime. Criminology, 1–43.

1 INTRODUCTION Sources of social control reach well beyond the criminal justice system. One such source is private citizens serving as guardians who disrupt a criminal event or avert situations that could escalate into crimes. The concept of guardianship, initially proposed by Cohen and Felson (1979), is a fundamental aspect of routine activities theory (RAT) and forms the foundation of various crime prevention policies.