Where America goes, the rest of the world tends to follow.
Americans have always had an equivocal attitude towards democracy. On the one hand, they're democratic to a fault, electing rather than appointing all sorts of officials (although not dogcatchers, notwithstanding the saying that so and so "couldn't be elected dogcatcher".)
On the other, their suspicion of government and willingness to believe the worst of those they elect indicate a lack of faith in the system and their own judgment.
A component of this negativity is the view of Washington as a cosy club where principles are purely for show and the legislative process is a succession of "you scratch my back, I'll scratch yours" deals made behind closed doors in smoke-free rooms.
The enduring influence in popular culture of Frank Capra's 1939 movie Mr Smith Goes to Washington, starring Jimmy Stewart as the young straight-arrow senator overwhelmed by venality and corruption, suggests this perception of how Washington works is deeply embedded in the American psyche.
This, in turn, reflects a view of Washington itself as a political Bermuda Triangle where principles disappear without trace. (The political class has contributed to this perception: "Running against Washington" is a tried and tested campaign strategy.)
It also, and more problematically, reflects an aversion to compromise and consensus politics.
Which is where the Tea Party comes in. Wrapped in a star-spangled banner of self-righteousness and armed with cast-iron conviction, the hallmark of ignoramuses and fanatics, the Tea Party is on a crusade to restore "true American values".
The corollary of this world-view is that anyone who doesn't agree with them is "unAmerican".
It doesn't take much imagination to see how this approach is incompatible with the democratic process as we know it.
Democracy resembles sport in that both depend on the participants playing by the rules, abiding by the referee's decision and accepting the outcome.
The Tea Party-aligned faction of the Republican Party has forced a government shutdown because Obama and the Democrats won't gut the Affordable Health Care Act aka Obamacare, or won't delay its implementation so the Tea Partiers can gut it.
They portray Obamacare as sinister, alien and authoritarian even though the Democrats had been trying to introduce something similar for the best part of a century, and despite it bearing an uncanny resemblance to the Massachusetts health care scheme introduced by former Governor Mitt Romney - the Republicans' 2012 presidential candidate.
Health care reform was part of Obama's platform when he was elected in 2008; it then passed through the difficult legislative process to become law.
The Republicans themselves made last year's presidential election a quasi-referendum on Obamacare. By going to such lengths to obstruct it, they are declaring they're no longer bound by the rules of the game.
Their methods - forcing a government shutdown, playing fast and loose with the US and therefore global economies over the debt ceiling - amount to hostage-taking: if you don't give us what we want, we'll burn the house down.
When it involves guns and bombs and people dying, we call this sort of behaviour terrorism. It shouldn't need to be said that terrorism is the antithesis of democracy.
Ultimately democracy is a means of managing divergence of opinion and ensuring the divisions which exist in all societies don't lead to conflict.
It assumes that over time support for the broad political philosophies will ebb and flow, so no movement or party will have a monopoly on power.
The Republicans are effectively saying that they're not prepared to wait for the electoral cycle to work in their favour - they want to call the shots even when they lose. It's important for all of us that they don't get away with it.
