"When I was a boy of 14, my father was so ignorant I could hardly stand to have the old man around. But when I got to be 21, I was astonished at how much the old man had learned in seven years."

So wrote Mark Twain in a famous quote whose first half could be an epitaph for this week's Republican primary defeat of 80-year-old Sen. Richard Lugar of Indiana.

It's an open question whether the tea party — the primary force in Lugar's defeat — is anything like Mark Twain at 14, but right now, it struts and frets with every attribute of an adolescent.

Adolescents are grandiose. They have an overblown sense of their own power. They believe they have nothing to learn from their elders. They decry any knowledge that doesn't come from their peers. They believe they're immortal, so they're reckless. They laugh at consequences. They dismiss long-term plans. They demand instant gratification. They love to mock others, and they fear being seen with anyone outside the cool group.

A related trait of adolescents is their budding capacity for reason. They are able to articulate political principles, apply them and embrace them as virtues. But adolescents are not yet skilled at weighing the consequences of applying a principle under certain conditions. Nor are they good at prioritizing — managing the interplay between competing principles. Nor are they very skillful in looking within and exploring how consistently they practice the principles they espouse. Despite these limitations, they are little troubled by doubt, as long as, paradoxically, their lack of doubt is endorsed by their peers.

Those tendencies can explain why some tea party members would passionately support Herman Cain for president — convinced that he is as capable as anyone for the job. They explain why a tea partyer might resist any deal on raising the debt ceiling, convinced that the consequences of a default don't matter. They explain why a tea partyer might reject any tax increase, even as he makes it a high principle to reduce the deficit. Finally, they explain why a tea partyer would scorn compromise, convinced that any deal struck with people outside his group betrays his cause.

More immediately, those tendencies explain why tea partyers would vote for Republican Senate candidate Richard Mourdock over Richard Lugar even though Lugar's defeat removed one of the most knowledgeable foreign policy voices in the Senate, cost Indiana influence and seniority in Washington, and increased the chance that a Democrat will win Lugar's seat.

Mourdock has said, "The time for being collegial is past; it's time for confrontation." He also has said, "The most powerful people in both parties are so opposed to one another that one side simply has to win out over the other." Mourdock also opposed the auto bailout, even though it saved thousands of good Indiana jobs during a severe downturn. Those statements and actions are very appealing to a mindset that touts its love of principle and then embraces only one principle among many in play.

After his election defeat, Lugar said: "If Mr. Mourdock is elected, I want him to be a good senator. But that will require him to revise his stated goal of bringing more partisanship to Washington. ... Unless he modifies his approach, he will achieve little as a legislator."

Spurning this advice, Mourdock reaffirmed his stance: "I have a mindset that says bipartisanship ought to consist of Democrats coming to the Republican point of view."

The tea party can be expected to swagger. It is a young movement that has made a big political impact in a short time. Most groups with such early success would act in the same way. But gaining political power is an easy task compared with the more important task of using that power to make the country stronger. The second task calls for different skills. Unlike tea partyers, Mourdock may be legislating in the Senate soon, and he ought to know the difference.

As if it were a defense of partisanship, Mourdock told CNN, "The fact is you never compromise on principles." No responsible person is asking Mourdock to give up his principles; he just needs to add one: It would be good of him to show a little humility and — in the words of Ben Franklin — "pay more respect to the judgment of others." They might have some insights that he does not, and it's their country, too.

Tom Rosshirt was a national security speechwriter for President Bill Clinton and a foreign affairs spokesman for Vice President Al Gore. Email him at [email protected]. To find out more about Tom Rosshirt and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate Web page at www.creators.com.