Many political libertarians argue, or assume, that negative moral duties (duties not to harm others) prevail over positive moral duties (duties to aid others), and that the legal system ought to reflect such pre-eminence. I call into question this strategy for defending a libertarian order. I start by arguing that a successful account of the well-known case of a runaway trolley that is about to kill five innocents unless a passer-by diverts it onto one innocent, killing him, should point to (...) (i) the ex ante advantage to all six of being subject to a policy of redirection of runaway trolleys, and (ii) the causal structure of killing vs. letting-die choices. I then argue that this account of the trolley case entails that legal systems reflecting the relative stringency of negative and positive moral duties should uphold redistributive measures at odds with libertarianism. The assumption that the legal system ought to reflect, through non-causal routes, moral principles and their relative weights leads to either an ideal-theory (in Rawls's sense) assessment of libertarianism or a symbolic account of the relationships between morality and law. Libertarians should undermine this assumption if they hope to offer an all-things-considered case for free markets. (shrink)

In this essay I dispute the widely held view that utility theory and decision theory are formalizations of instrumental rationality. I show that the decision theoretic framework has no deep problems accommodating the ?reasonable? qua a preference to engage in fair cooperation as such. All evaluative criteria relevant to choice can be built into a von Neumann?Morgenstern utility function. I focus on the claim that, while rational choice?driven agents are caught in the Pareto?inferior outcome, reasonable agents could ?solve? the PD (...) and cooperate. Not so, I argue. If reasonable people find themselves in PD situations they too would follow the dominant ?defect? strategy. The difference between instrumentally rational agents and those who are also reasonable is not that they would behave differently in Prisoner?s Dilemmas, but that reasonable people are more successful at avoiding the Prisoner?s Dilemma and tend to play more cooperative games. (shrink)