It’s highly improbable, to put it politely, that the junior senator from Kentucky will be the next president of the United States. Yet Rand Paul’s campaign, announced Tuesday, is not quixotic. To the contrary, Paul’s candidacy matters.

Quite aside from the merits (or absurdity) of his ideas, Paul is pushing his fellow Republicans to question both their politics and their policies. And the country itself benefits when it has a strong two-party system that forces Democrats as well as Republicans to clarify their thinking.

Even when he’s wrong, as he is on the need to audit the Federal Reserve, Paul rarely repeats the lazy slogans that mark so much political debate. Meanwhile, his skepticism about the surveillance state, like his skepticism that U.S. military engagement is a corrective to seemingly every foreign circumstance, is a valuable contribution to the Senate (and will make life uncomfortable not only for many of his fellow Republican candidates but also for presumptive Democratic nominee Hillary Clinton).

In addition, tone matters. Paul generally has the bearing of a happy warrior, engaging his fellow citizens rather than heaping contempt on opponents. It’s a temperament that serves him, and U.S. politics, well, and one that some of his more surly primary opponents should emulate.

In that vein, Paul’s efforts to expand the Republican brand to young people and racial minorities are both brave and necessary. Critics have questioned the sincerity of his appeals to black audiences, including a speech at Howard University. But even at the level of symbolism and showmanship, Paul’s outreach is valuable.

Symbols matter; so does showing up. The U.S. faces a difficult future if its two main political parties grow more racially polarized. In a speech at the University of California, Berkeley, Paul said his party must “evolve, adapt or die” given demographic realities. Similarly, his support for sentencing reform and questions about his party’s efforts to make voting more difficult suggest the possibility of new pathways to new voters.

The danger is that Paul’s ambition will constrain his usefulness. Shortly after he questioned Republicans’ focus on combating virtually nonexistent voter fraud, for example, Paul retreated, perhaps fearful of alienating his party’s base. Paul can do far more good stretching the Republican Party’s ideological straitjacket than he will ever do wearing it.

The renewal of the Republican Party cannot happen without some serious awkwardness and conflict. Paul may be an imperfect vessel of Republican hopes. But to the extent that he challenges some of the orthodoxies inhibiting the party’s evolution and opens it to more diverse views, he is an invigorating addition. Welcome to the 2016 race, Senator.