Since the 2008 election, American conservatism has been in a struggle to define itself. Now the selection of Paul Ryan as Mitt Romney's vice presidential candidate is helping to resolve that struggle.

For years, the political left has tagged conservatives as out-of-touch anarcho-capitalists, all while enjoying a Republican party that, in reality, has demanded little more than a marginally more efficient administration of the welfare state than what the Democrats want. Conservatives have tried in vain to find a voice that refutes both caricature and reality.

Now, Paul Ryan has found what may be the right approach, and Mitt Romney has installed it at the center of the Republican party before it is too late to save the country from a European-style debt crisis.

“Ryanism” celebrates private entrepreneurship, demands lower taxation, and is willing to take on the hard issues of structural reform to programs, including out of control entitlement spending. It seeks to protect the social safety net by limiting it to the truly indigent and not to allow it to become a source of middle class entitlement (as it has over the last few decades). It does not "end Medicare," but rather makes changes to the system for those under age 55 so the program is solvent and does not rob our children. It is unashamed of America's powerful position in the world and recognizes that military spending is—when pursued prudently and not wastefully—a public good and not just another government boondoggle.

In other words, the Ryan approach is conservative and, very likely, workable. That is why it is so feared and loathed by the left.

Shortly after the announcement of Ryan's vice presidential candidacy, Obama advisor David Axelrod characterized Ryan's budget ideas as "trillions of dollars of new tax cuts skewed to the wealthy that are paid for by cuts in college scholarships and loans and student aid and Medicare and nursing home care for seniors, and the things we need to grow like research and development and new American energy."

Even more telling, Ryanism's alarming ascendancy has stripped the veneer off some centrist groups long-believed by some on the right to front for liberal policies. For example, the cofounder of the nonpartisan self-described "moderate" organization Third Way has described Ryan as a "radical and a bomb-thrower." (So shrill have the organization's attacks on Ryan been that they provoked long-time Third Way donor and trustee Daniel Loeb, a New York financier, to resign his board membership in disgust, writing, "I can no longer support a group which is in the back pocket of this administration.")

In fact, the left's alarm is well founded. While the old GOP created little impediment to the liberal policy agenda, Ryanism poses a major threat to the forces of American social democracy over the coming decades. Further, Ryan himself is the walking refutation of the elite liberal narrative that true conservatives are basically unsophisticated rubes.

We do not yet know whether Mitt Romney's public embrace of Ryanism will move the polls for or against Obama enough to have an effect on the election. Perhaps Democrats will be able to convince Americans that Ryan is the scary ideological love child of Ayn Rand and Ludwig von Mises. Or maybe swing voters find the left's attacks unconvincing. Time will tell.

But there is guaranteed good news here for conservatives, no matter what happens in the November election. Millions of American conservatives will finally have something to vote for, instead simply of something to vote against. Look for an uptick in right wing enthusiasm in the months to come as a result.

Romney has done much more than fill out his ticket. He has shown his intention to refocus American politics. Ryanism is now an official voice of establishment Republicanism. For the first time since Ronald Reagan, Americans might just find they have a national political party centered on free enterprise and American greatness.

Arthur C. Brooks is president of the American Enterprise Institute and author of The Road to Freedom: How to Win the Fight for Free Enterprise (Basic Books, 2012).