Over the last few election cycles, "fact checking" has become ubiquitous. News organizations, advocacy groups and partisans devote significant resources to comparing what is said in election campaigns to what happens after the winners take office. Not surprisingly, the reality of governing doesn't always match the promises that candidates make.
What most of the fact-checking sites and organizations have in common is that they are about correcting the record with respect to things that have already happened. There is another kind of reality check, however, that may be even more important but is much harder to do. That is when a candidate for office promises to do things, if elected, that would not pass any kind of reality check. Unlike untruths that are told about past events, we do not know that these are false, but there should be substantial reasons to very skeptical that these promises can ever come true.