Like criminal trials or major football matches or fights within marriages, presidential election contests in America are about both stated and unstated matters. The stated matters are the ones the candidates talk about and run on: the mess in Iraq, the terrorist threat, the healthcare crisis and so on.
The unstated questions are the ones candidates are loth to discuss themselves but that aren't too far from the surface and are deeply felt by the partisans on both sides. These have to do with the "mood" of the broader public at election time and with what an electoral outcome "says" about large historical shifts. For example, the British election of 1945 confirmed a desire among voters for social reform so profound that it swept aside a great national hero. Similarly - except in the other direction ideologically - American voters made a statement in 1980 when they voted Ronald Reagan into the White House by a landslide proportion, signalling that one era was over and another one dawning.
Will 2008 be such a year? The question is on the minds and tongues of many in Washington. Liberals hope that the answer is yes, while conservatives fear that it is (and conservatives seem more uniformly pessimistic than liberals seem optimistic).
But how might we know that 2008 is such a year? Let me offer what I think is the most important undercurrent question of next year's election: have Americans tired of conservatism, or have they merely tired of corrupt and incompetent conservatism?
Modern "movement conservatism" was born in the 1950s. Because its founders, men like William F Buckley Jr and Russell Kirk, claimed as their predecessors not politicians so much as thinkers - Burke, Oakeshott, Hayek and von Mises - movement conservatism had, in essence, no experiential political history. It was a new thing.
By 1964, conservatives were able to nominate one of their own, Barry Goldwater, for president. But it took them another 16 years to elect a president, Reagan. And then it took another 14 years before Republicans led by Newt Gingrich took control of the House of Representatives, for conservatives to seize power at a level below the presidency. In all that time, your "average"- that is, nonpolitical - American had no deeply negative experience of movement conservatism. It wasn't quite the golden age that today's embattled conservatives contend it was; for example, Reagan left office with a lower approval rating than Bill Clinton did.
Nevertheless, most average people found the experience of conservative governance more positive than not: Reagan cut their taxes, stared down the Russkies and made them feel good about their country. Even Gingrich and his cohort, before being laid deservedly low by their obsession with Clinton's sex life, were credited by your average Joe with having cleaned out the Augean stables of Democratic Washington.
Then came Bush. At first things were motoring along nicely, and Bush guru Karl Rove's prediction that a permanent conservative majority was coalescing seemed probable. Now it has all crashed and burned for the reasons we know about. But we still don't know what exactly is that "it".
That is, Americans have now experienced a conservative government failing them. But what lesson will they take? That conservatism itself is exhausted and without answers to the problems that confront American and the world today? Or will they conclude that the problem hasn't been conservatism per se, just Bush, and that a conservatism that is competent and comparatively honest will suit them just fine?
Conservatives and the Republican presidential candidates hope and argue that it's the latter. They largely endorse and in some cases vow to expand on the Bush administration's policies - Mitt Romney's infamous promise to "double" the size of the detention camp at Guantánamo Bay, notably. Like Bush, they vow that tax cuts, deregulation and smaller government will solve every domestic problem. Where they try to distinguish themselves from Bush is on competence. Romney talks up his corporate success, Rudy Giuliani his prowess as mayor of New York.
The Democrats aren't as full-throated in opposition to all this as one would hope - they dance away from the word "liberal" and they don't really traffic in head-on philosophical critiques of conservative governance. That said, though, all the leading Democrats are running on pretty strongly progressive platforms.
On healthcare, energy and global warming, all promise a very different direction for the country. Hillary Clinton has even inched to her husband's left on trade issues. Even given her innate caution and rhetorical hawkishness on foreign policy, it's fair to say that Clinton, Barack Obama and John Edwards are making a forceful case for a clean ideological break.
The rubber will hit the road next summer and autumn. Then the Republicans will tell voters that the Democratic nominee has proposed trillions of dollars' worth of new programmes and will inevitably raise taxes to pay for them. The Democrat will need to stand her or his ground and, while obviously not being cavalier about taxes, present a vision of a different kind of society. There are signs that 51% of the voters may be ready to embrace it.