Is Samuel Johnson's quote a valid or true statement? I understand your central thrust--the inability to do something personally (such as control one's sexual urges) and the disposition to encourage others to overcome that inability are not necessarily contradictory--indeed, they may fall together naturally. However, in Samuel Johnson's world, and the world in which this "issue" comes up the most, politics, we might imagine that there exist two types of people: sociopathic individuals hungry for power, and individuals who are sincere. If sociopathic individuals hungry for power are more often hypocrites, then we might, as an efficient rule of thumb (not being able to distinguish the two save through their observable actions!) condemn hypocrites because they are likely to be power-hungry individuals. As a bayesian update, in the world of politics, we expect that hypocrites are more likely to be power hungry or sociopathic. I see Samuel Johnson's quote as potentially true, but ignoring a world of imperfect information and signaling.