Why does the most highly advanced industrial country, commanding unparalleled access to vast sources of global intelligence and information, seem to so often miscalculate the realities and risks of its foreign interventions? In light of current difficulties the United States faces in extricating from its recent interventions in Iraq and Afghanistan, and in dealing -or not dealing -with the tumultuous and complicated events of the Arab Spring, one has to ask what can possibly account for so little apparent evolution. In Tyranny of Consensus, Janne E. Nolan examines three cases -the Islamic Revolution in Iran, the proxy war with the Soviet Union in Afghanistan, and the 1998 embassy bombings in East Africa -to find the limitations of American policymakers in understanding some of the important developments around the world. Assisted by a working group of senior practitioners and policy experts, Nolan finds that it is often the impulse to protect the already arrived at policy consensus that is to blame for failure. Without access to informed discourse or a functioning ""marketplace of ideas,"" policymakers can find themselves unable or unwilling to seriously consider possible correctives even to obviously flawed strategies.