Remember the Y2K bug? And the US "debt ceiling" crisis?

Of course you do, but only as historical curiosities, not as events that brought civilisation to its knees.

It didn't seem like that at the time, of course – countless hours of worry and commensurate swings in the stock market were devoted to these two topics.

What about the wars in Iraq and Afghanistan, or the 9/11 attacks on the United States?

Awful situations, all, which bought with them (as a very minor consequence) swooning share prices and fears of economic collapse.

The one no one saw coming

The event which really did hit stock markets for six? The collapse in US house prices, brought on by irresponsible lending, which led to bank failures. Ditto bank and government failures in Europe.

So despite all of the fear and short-term panic brought about by those things we thought we could foresee, it was the one we didn't pick – an unsustainable debt bubble in all of its forms – that did the damage.

Which brings us to the imaginatively-titled "fiscal cliff" in the US.

Lest you think this is some "fall-to-the-death" event, the impact of the worst-case-scenario is economic contraction of about 5 per cent.

Not exactly a "cliff"

If you're wondering, this "cliff" is the confluence of tax increases and government spending reductions that are all scheduled to commence from January 1, 2013, unless the US Congress takes action.

The increase in taxation will remove some discretionary spending from the economy, while the reduction in government spending will do the same. Reduced demand would follow, and the flow-on impact would be significant.

Yes, incredibly unwelcome, and it would set the US recovery back a few years, but it's hardly the stuff of Armageddon.

Of course, the impact is largely irrelevant. This particular situation is eminently understandable and, more importantly, avoidable. The circumstances and the solutions – even if only temporary – are known. They are also under the control of a small number of people, who, even if they argue about how to fix the problem, aren't stupid enough to let the worst-case come to pass.

Bluff and bluster

The logic is pretty simple. Humans – especially politicians – understand the basic instinct of self-preservation. Only in the most dire and unusual of circumstances do we have a "we have to destroy the village to save it" outcome, and popularly elected officials aren't crazy enough to damage the United States' near-term future, and with it, their own political careers.

Yes, the fiscal cliff could be serious, if left untreated. But so can inflation, unemployment, termites and a whole host of potentially serious diseases. But we don't leave those things untreated.

Each is unpleasant if left to its own devices, so we don't leave them to their own devices!

The sky isn't falling

Since President Obama's re-election, the market has taken a pessimistic turn – the Republican-controlled House of Representatives and the Democratic Senate and presidency were seen as signs of potential instability.

Then, overnight, amid reassuring words from US politicians, the S&P 500 jumped 2 per cent. Our market enjoyed a little of that glow this morning, up a more moderate 0.4 per cent at lunchtime.

The Y2K bug was treated before it was allowed to disrupt much at all. The debt ceiling was little more than political brinksmanship writ large, before the inevitable compromise was reached.

Like the old joke that economists have picked nine of the past two recessions, the existence of a possible risk is far from the same thing as that risk being realised.

Foolish takeaway

The end result of the current impasse is easy to predict – it will be solved before it becomes a real problem. How and exactly when is uncertain, but from an investing perspective, it's also largely irrelevant.

If the market wants to panic, at The Motley Fool we'll happily take advantage of lower prices. When investors come back to their senses, either before or after the deal is done, we'll be glad we did.

Sensible investors should be doing exactly the same.

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Scott Phillips is a Motley Fool investment analyst. You can follow Scott on Twitter @TMFGilla. The Motley Fool's purpose is to educate, amuse and enrich investors. This article contains general investment advice only (under AFSL 400691).