In the wonderfully funny movie “Mom and Dad Save the World,” one of the heroes admits that his people are not so bright. “But what we lack in brains,” he says, “we make up for in ...good intentions.” Gentle mocking here of the frequent appeal of the incompetent for tolerance of their mistakes: How can you blame us if our intentions are good? The trouble is that much of what's really rotten in the world is due to people who thought that their good intentions would ensure a favorable result. Maybe the best example of this: former president Jimmy Carter....