O Warneryd—The Economics of Conflict PROPERTY OF MIT PRESS: FOR PROOFREADING AND INDEXING PURPOSES ONLY 9 Social Preferences of Ex-Combatants: Survey and Experimental Evidence from Postwar Tajikistan Alessandra Cassar, Pauline Grosjean, and Sam Whitt 9.1 Introduction This chapter uses unique game-behavioral and survey evidence col- lected in postwar Tajikistan with the goal of better understanding the relationship between violence and pro-social behavior and, ultimately, the implications of violent conflicts for market development and insti- tution building. Recent studies have found surprising increases in pro-social behav- ior following exposure to violence, providing micro-level explanations for how societies might recover and develop even after devastating experiences (Bauer et al. 2011; Bellows and Miguel 2009; Blattman 2009; Voors et al. 2011). War has also been suggested to play a critical role in many macro-historical accounts of how nations develop and how polit- ical order and institutions are established within complex societies (Tilly and Ardant 1975; Tilly 1985; North, Wallis, and Weingast 2009; Fukuyama 2011). In some cases, however, the prospects of recovery from violence are not as promising. Some states appear deeply mired in poverty and stagnation, and in the worst cases, succumb to recurrent conflict and insurgencies (Collier et al. 2003; Collier and Hoeffler 2004). The main hypothesis defended in this chapter and in a companion paper (Cassar, Grosjean, and Whitt, forthcoming) is that violence creates long-lasting divisions in pro-social preferences of individuals diversely affected by the war toward different groups—which we call the conflict gap. From a theoretical perspective, an important foundation for our hypothesis comes from the culture/gene evolutionary approach to understanding human cooperation. A fascinating hypothesis is that intergroup conflict, like evolutionary pressures, fuels antipathy toward outsiders but reinforces cooperation toward insiders, a behavior known as parochial altruism (Bowles 2008; 2009; Choi and Bowles 2007; Boyd