ACTUALLY, OUR JOB IS TO FOLLOW WHERE OTHER STATES HAVE INNOVATED ALREADY:

We cannot realistically solve our problems by trying to return to the 3.0 liberalism of the 19th century because the American economy of that era depended on conditions we cannot reproduce today. Though some may think it desirable, we cannot return to a largely agrarian economy. Nor can we replicate the industrial system of the 19th century, with its extremely high tariffs against foreign goods and a completely laissez-faire national attitude toward immigration. Trying to recreate the American economy of a century ago would lead to massive dislocations, depressions and quite likely wars around the world, not to mention thoroughly wrecking the American economy and bankrupting many of our banks and biggest corporations.

But if red liberal fundamentalism can't work, blue fundamentalism can't help us either. There's no going back even half a century ago, because the great achievements of blue liberalism were also rooted in conditions we cannot replicate today. Between 1914 and the 1970s, when the blue social model took shape and rose to power and success, the world economy was in an unusual state. International financial and trade flows were much lower than before 1914 and after 1970, due to the disruptions of two world wars and the Great Depression. And the United States was so far ahead of the rest of the world in manufacturing that few American companies (or workers) had anything to fear from foreign competition. Capital was dramatically less mobile; it was much easier to tax high earners without driving savings and investment out of the country.

At the same time, Americans in the first two thirds of the last century were more willing to engage in group politics than is the case today. Industrial workers fought to build unions and generally voted the way their leaders advised them. Ethnic groups stuck together and voted as blocs. Twentieth-century liberal politics generally involved negotiated agreements among party bosses and other leaders who commanded loyal followings. Few politicians today can count on this kind of unquestioning support in an era when party structures and patronage networks are both weaker and less reliable than they used to be. Now, instead of party structures funding candidates, candidates are expected to fund party structures.

We must come to terms with the fact that the debate we have been having over these issues for past several decades has been unproductive. We're not in a "tastes great" versus "less filling" situation; we need an entirely new brew. But this is nothing to mourn, because both liberalism 3.0 and 4.0 died of success, just as versions 1.0 and 2.0 did before them.

As for 3.0, rising agricultural productivity ultimately drove millions of farmers off the land; high tariffs helped attract tens of millions of immigrants; ideas and institutions developed in a homogeneous, egalitarian and predominantly agricultural country no longer worked very well in an industrial, urban country threatened by class conflict. The same with 4.0. Our successful manufacturing economy led us to push for free trade; that stimulated other countries to export to U.S. markets and generated the kind of financial flows that undermined the nation-based Keynesian economic models of the 4.0 econ wizards. The rising affluence of Americans facilitated their mass migration into the suburbs where the old party organizations and ethnic loyalties broke down. More affluent and better educated voters became more individualistic and saw the system of party bosses as an obstacle to democracy rather than a way of making it work. Each version of liberalism in turn created a social system and an economy so dynamic and so inventive that it ultimately outgrew the institutions and ideas that had given it birth. Textbook cases of the cultural contradictions of capitalism at work they were.

Now it has happened again. The success of our institutions and ideas has so changed the world that they don't work any more. We cannot turn back the clock, nor should we try. America's job is to boldly go where none have gone before, not to consume our energies in vain attempts to recreate the glories of an unattainable past. We need to do for our times and circumstances what other Americans have done before us: Recast classic Anglo-American liberal thought, still the cultural and moral foundation of American life and the source of the commonsense reasoning that guides most Americans as they evaluate policy ideas and party programs, in ways that address the challenges before us.

For those blue Democrats clinging to liberalism 4.1, this is a time of doom and gloom. For those red Republicans longing for a return to liberalism 3.0, it is a time of angry nostalgia: Ron Paul making a stump speech. This should be a time of adventure, innovation and creativity in the building of liberalism 5.0. America is ready for an upgrade to a new and higher level; indeed, we are overdue for a project that can capture the best energies of our rising generations, those who will lead the United States and the world to new and richer ways of living that will make the "advanced" societies of the 20th century look primitive, backward and unfulfilled.

We've wasted too many years arguing over how to retrieve the irretrievable; can we please now get on with the actual business of this great, liberal, unapologetically forward-looking nation?

Follow @brothersjudd