The rise of civilizations involved the dual emergence of economies that could produce surplus ("prosperity") and states that could protect surplus ("security"). But the joint achievement of security and prosperity had to escape a paradox: prosperity attracts predation, and higher insecurity...

We develop a theoretical model of security investments in a network of interconnected agents. Network connections introduce the possibility of cascading failures due to an exogenous or endogenous attack depending on the profile of security investments by the agents. The general presumption in...

From 2000 to 2010, more than 20 states passed laws that make it easier to use lethal force in self-defense. Elements of these laws include removing the duty to retreat in places outside of one's home, adding a presumption of reasonable belief of imminent harm, and removing civil liability for...

Evaluations of changes to the Medicaid program have focused on increases in the generosity of income cutoffs for Medicaid eligibility. Previous research shows that despite dramatic increases in the number of births paid for by the Medicaid program, women often enroll in Medicaid at the point of...