The 1987 stock market crash was Made in America. On the face of it, this year's equivalent carries a Made in Thailand label. But where next for the investor? That label is counterfeit. It is wrong to see the slide of the past few days as the result of contagion from Asia. Wall Street's current setback is just as star-spangled as it was in 1987.

The Asian market weakness was not important in itself. Rather, it was the external signal that alerted US investors to their long-suppressed qualms.

Still, though the US drop this week was grounded in US circumstances, it shares some underlying themes with the emergingmarket turmoil. The interaction between four themes disinflation, globalisation, the appetite for risk, and the belief in "new paradigms" explains both the remarkable prosperity of financial markets in recent years and this week's abrupt set-back.

The shift of government policy and market expectations towards disinflation since the mid-1980s remains the most powerful underlying trend. though not Japan have experienced this trend almost entirely as good news. Interest rates have fallen, government spending has been reined in, wage demands have lessened, raw material prices have stayed low. Financial markets have rejoiced in consequence. But disinflation carries a price. As Japan and, indeed, continental Europe have found, it is easy to slip from disinflation to deflation, and hard to escape.

The second big theme, globalisation, is closely tied to the disinflation trend. The integration of emerging markets of all kinds into the global economy has helped hold down price pressures in the developed world. It has encouraged a flood of investment into the rapidly growing economies of South East Asia and Latin America, and the recovering economies of central and eastern Europe. In Asia, at least, this process contributed to an asset price bubble that finally burst this year.

The third underlying trend is the appetite for risk. All great financial-market cycles can be traced to the ebb and flow of this sentiment.

The fourth theme is the belief in new paradigms. Millennarian optimism has provided a surfeit of such visions. The technology-based transformation of the US economy. Asia as the manufacturing workplace of the world economy. A new, flexible, competitive Britain. The virtual company. The global consumer. The service-based economy. And so on.

Paradoxical as it may seem, new paradigms cause problems not when they are wrong, but when they are manifestly right. Long-term trends, by definition, work in the long term. Yet, in Asia until the spring and in the US this summer the markets have been treating the long term as if it was already here.

So what happens now? Mood and crowd psychology will drive the events in the short term. But beyond them, a few fundamental questions can be robustly answered. For example: the Asian growth miracle is not over, grim though things may look for the moment. Rebuilding battered financial systems in the worst-hit Asian economies especially Thailand - will take time.

But the inventiveness, flair and determination of individual entrepreneurs across the region is unchanged. And they are now operating in cheaper currencies.

Similarly, emerging-market investment will continue to grow, even if the events of the past few weeks create a temporary hiccup. So much for the trends in emerging economies. In the developed world, the debate about what happens next is dominated by the legacies of the two most commonly cited market set-backs: 1929 and 1987. The fear engendered by 1929 is of a deflationary spiral, a collapse of the banking system, and a worldwide resort to protectionism. The fear inherited from 1987 is the opposite: to avert the risk of repeating 1929, the authorities loosen monetary policy too much, creating a resurgence of inflation which only a sharp recession will eliminate.

Today's market valuations - particularly in the US - depend heavily on the belief in steady, inflation-free growth. If investors came to suspect that the Federal Reserve was repeating 1987's approach, that belief would vanish, with damaging consequences for both bond and equity prices.

Even without a mis-step by central bankers, financial markets might find the next few years stressful. Paradoxically, a rapid rebound - fuelled by investors intrigued by a buying opportunity - might in the long run prove the least desirable outcome. Sentiment of this sort might prove resilient enough to confine true crashes to less liquid, more marginal emerging markets. But, as long as systemic collapse can be avoided, there are worse things than a short, sharp adjustment..

These are the uncertainties to be resolved in the days ahead. All are hard to forecast, but one thing can be said with confidence: none of them will be decided in Thailand.