"An observer of this summer’s party conventions would get the idea that the use of military force is almost always and everywhere wrong and ill-advised. Any reference to the use of force was drowned out at the conventions by chants of America First and no more war. With the exception of Donald Trump's open-ended threat to knock the hell out of ISIS, there seems to be a political consensus that the use of force is almost never a good idea.
On the campaign trail both candidates have reinforced this view, often promoting a false choice between rebuilding America and being the world's policeman.
Is the use of force a defensible foreign policy tool and, if so, when and why? There are two main arguments against the use of force, either in specific instances or as a more general policy. The first is pragmatic. Are the goals of the use of force vital to America's national security? If so, are these goals important enough to justify the likely costs in terms of American lives and treasure? And if they are, can policymakers be relatively confident the use of force will achieve their aims, without unintended and destructive consequences beyond the immediate military objective? These are serious questions, to which we shall return."