The process of evaluating presidential candidates always involves a lot of speculation and guesswork, because we can't know what conditions a president is going to confront a few years from now. On domestic policy, however, we can at least look at what the candidate says he wants to do, because candidates keep the vast majority of their campaign promises. Barack Obama said he would enact health care reform, and he did; George W. Bush said he'd cut income taxes, and he did. When it comes to foreign policy, though, it can be a lot tougher to discern. First, candidates tend to be a lot less specific about what they intend to do. And second, much of foreign policy involves reacting to developments no one can foresee. So if you're trying to figure out what, say, Jeb Bush would do in foreign affairs, what do you have to go on? Well, you can ask a question like, "Would he be more like his father, or more like his brother?" Which will tell you very little. But Michael Crowley gives it a shot...