This is part of IEEE Spectrum's SPECIAL REPORT: THE SINGULARITY

Image: Bryan Christie Design

Our global economy would stupefy a Roman merchant as much as the Roman economy would have confounded a caveman. But we would be similarly amazed to see the economy that awaits our grandchildren, for I expect it to follow a societal discontinuity more dramatic than those brought on by the agricultural and industrial revolutions. The key, of course, is technology. A revolutionary speedup in economic growth requires an unprecedented and remarkable enabling tool. Machine intelligence on a human level, if not higher, would do nicely. Its arrival could produce a singularity--an overwhelming departure from prior trends, with uneven and dizzyingly rapid change thereafter. A future shock to end future shocks.

Yes, this theory of mine is a social and economic one, and therefore not as unfailingly accurate or testable as one in the physical sciences. Nevertheless, social scientists routinely make short-term forecasts that hit the mark, and economists often offer insightful forecasts about unprecedented situations.

So indulge me as I outline how we economists view technological change. In so doing, I hope to explain why it's reasonable to view past history as a series of abrupt, seemingly unheralded transitions from one economic era to another, transitions marked by the sudden and drastic increase in the rate of economic growth. I will then show why another singularity is perhaps just around the corner. Finally, I will outline its possible consequences.

A complex device, like a tractor or a building, can have thousands of parts, and each part can rely on dozens of technologies. Yet in most cases even a spectacular gain in the quality of one part bestows at best only a small improvement on the whole. Keep improving a part in successive increments of equal degree and you'll get ever smaller gains to the whole. This is the law of diminishing returns, and it applies not only to devices and organizations but to entire industries. Consider your personal computer: every couple of years its power-to-cost ratio has doubled, and yet as you go from one generation to the next, you probably notice only a small improvement as you plug away on your word processors and spreadsheets.

It turns out that most of these small, innovative gains come not from research labs but from hands-on builders and users. So the more a thing gets used, the more it tends to improve. It doesn't matter whether that thing is a physical device, such as a car, or a social organization, such as a corporation.

If any large system of interacting parts tends to improve by smooth gradations, then we should expect systems of systems, with their larger number of components and interactions, to improve even more smoothly. By this reasoning, the world economy should improve most smoothly of all. The world economy consists of the largest number of interacting parts of any man-made system, and everyone not stranded on an uncharted island contributes to the improvements in all those parts by using them. Finally, in each economic era the question of whether growth speeds up or slows down depends on two competing factors. Deceleration typically ensues as innovators exhaust the easy ideas--the low-hanging fruit. But acceleration also ensues as the economy, by getting larger, enables its members to explore an ever-increasing number of innovations.

The world economy, which now doubles in 15 years or so, would soon double in somewhere from a week to a month.

We have the tools to measure the world's economic product not only for today--it's about US $50 trillion per year--but also for times long past. A few years ago Angus Maddison, an economic historian at the University of Groningen, in the Netherlands, plotted a graph of world economic product--basically everything of value produced globally: bananas, submarines, magazine articles, you name it. It shows that from 1950 to 2003, growth was relatively steady. During that time, despite enormous technical change, no particular technology left much of a fingerprint on the data; no short-term accelerations in growth could be attributed to this or that technological development. Also, Maddison's data offer little support for the idea that innovation and growth have been accelerating recently.

Now look at the data for world product over the past 7,000 years, estimated by Bradford DeLong, an economic historian at the University of California, Berkeley. The data here tell a somewhat different story. For most of that time, growth proceeded at a relatively steady exponential rate, with a doubling of output about every 900 years. But within the past few centuries, something dramatic happened: output began doubling faster and faster, approaching a new steady doubling time of about 15 years. That's about 60 times as fast as it had been in the previous seven millennia.

We call this transition the Industrial Revolution, but that does not mean we understand it well or even know precisely how and why it arose. But whatever the Industrial Revolution was, clearly it was an event worthy of the name ”singularity.”

If we look further back, we see what appears to be at least one previous singularity--the transition to an economy based on agriculture. And slow as economic growth during the agricultural era may seem in the aftermath of the Industrial Revolution, it was actually lightning fast compared with that of the economic era that came before, which was based on hunting and gathering.

In the roughly 2 million years our ancestors lived as hunters and gatherers, the population rose from about 10 000 protohumans to about 4 million modern humans. If, as we believe, the growth pattern during this era was fairly steady, then the population must have doubled about every quarter million years, on average. Then, beginning about 10 000 years ago, a few of those 4 million humans began to settle down and live as farmers. The resulting communities grew so fast that they quickly accounted for most of the world population. From that time on, the farming population doubled about every 900 years--some 250 times as fast as before.

Our understanding of the existence, nature, and relevance of these transitions clearly becomes more speculative the further back we look in time [see sidebar, ”How Many Singularities Have There Been?”]. There may well have been two earlier singularities that started eras of this sort, although our ability to identify them and weigh their relevance is very speculative. I suggest an era defined by the growth of the brain from the emergence of animal life to the first protohumans and perhaps an earlier era defined by the growth of the universe from a time shortly after the big bang to the first animals.

So we have perhaps five eras during which the thing whose growth is at issue--the universe, brains, the hunting economy, the farming economy, and the industrial economy--doubled in size at fixed intervals. Each era of growth before now, however, has eventually switched suddenly to a new era having a growth rate that was between 60 and 250 times as fast. Each switch was completed in much less time than it had taken the previous regime to double--from a few millennia for the agricultural revolution to a few centuries for the industrial one. These switches constituted singularities.