CAMBRIDGE • We seem to be living in an accelerated age of revolutionary technological breakthroughs. Barely a day passes without the announcement of some major new development in artificial intelligence, biotechnology, digitisation or automation. Yet those who are supposed to know where it is all taking us can't make up their minds.
At one end of the spectrum are the techno-optimists, who believe we are on the cusp of a new era in which the world's living standards will rise more rapidly than ever. At the other end are the techno-pessimists, who see disappointing productivity statistics and argue that the new technologies' economy-wide benefits will remain limited. Then there are those - the techno- worriers? - who agree with the optimists about the scale and scope of innovation but fret about the adverse implications for employment or equity.
What distinguishes these perspectives from one another is not so much disagreement about the rate of technological innovation. The debate is about whether these innovations will remain bottled up in a few tech-intensive sectors that employ the highest-skilled professionals and account for a relatively small share of GDP or spread to the bulk of the economy. The consequences of any innovation for productivity, employment and equity depend on how quickly it diffuses through labour and product markets.
Technological diffusion can be constrained on both the demand and supply sides of the economy. Take the demand side first. In rich economies, consumers spend the bulk of their income on services such as health, education, transportation, housing and retail goods. Technological innovation has had comparatively little impact to date in many of these sectors.
Consider the figures provided by the McKinsey Global Institute's recent report Digital America. The two sectors in the United States that have experienced the most rapid productivity growth since 2005 are the information and communications technology and media industries, with a combined GDP share of less than 10 per cent. By contrast, government services and healthcare, which together produce more than a quarter of GDP, have had virtually no productivity growth.
Techno-optimists look at such numbers as an opportunity: There remain vast productivity gains to be had from the adoption of new technologies in the lagging sectors. The pessimists, on the other hand, think that such gaps may be a structural, lasting feature of today's economies.
For example, economic historian Robert Gordon argues that today's innovations pale in contrast to past technological revolutions in terms of their likely economy-wide impact. Electricity, the automobile, the airplane, air conditioning and household appliances altered the way that ordinary people live in fundamental ways. They made inroads in every sector of the economy. Perhaps the digital revolution, impressive as it has been, will not reach as far.
On the supply side, the key question is whether the innovating sector has access to the capital and skills it needs to expand rapidly and continuously. In advanced countries, neither constraint typically binds much. But when the technology requires high skills, its adoption and diffusion will tend to widen the gap between the earnings of low- and high-skilled workers. Economic growth will be accompanied by rising inequality, as it was in the 1990s.
The supply-side problem faced by developing countries is more debilitating. The labour force is predominantly low-skilled. Historically, this has not been a handicap for late industrialisers so long as manufacturing consisted of labour-intensive assembly operations such as garments and automobiles. Peasants could be transformed into factory workers virtually overnight. Manufacturing was traditionally a rapid escalator to higher income levels.
But once manufacturing operations become robotised and require high skills, developing countries lose their comparative advantage vis-a-vis the rich countries. We see the consequences in the "premature de-industrialisation" of the developing world today.
In a world of premature de-industrialisation, achieving economy-wide productivity growth becomes that much harder for low-income countries. It is not clear whether there are effective substitutes for industrialisation.
Economist Tyler Cowen has suggested that developing countries may benefit from the trickle-down of innovation from the advanced economies. They can consume a stream of new products at cheap prices. This is a model of what he calls "cellphones instead of automobile factories". But what will these countries produce and export - besides primary products - to be able to afford the imported cellphones?
In Latin America, economy-wide productivity has stagnated despite significant innovation in the best-managed firms and vanguard sectors. The apparent paradox is resolved by noting that rapid productivity growth in the pockets of innovation has been undone by workers moving from the more productive to the less productive parts of the economy - a phenomenon that my co-authors and I have called "growth-reducing structural change".
This perverse outcome becomes possible when there is severe technological dualism in the economy and the more productive activities do not expand rapidly enough. Disturbingly, there is evidence that growth-reducing structural change has been happening recently in the US as well.
Ultimately, it is the economy- wide productivity consequences of technological innovation, not innovation per se, that lifts living standards. Innovation can co-exist side-by-side with low productivity (conversely, productivity growth is sometimes possible in the absence of innovation, when resources move to the more productive sectors).
Techno-pessimists recognise this; the optimists might not be wrong, but to make their case they need to focus on how the effects of technology play out in the economy as a whole.
•Dani Rodrik, professor of international political economy at Harvard University's John F. Kennedy School of Government, is the author of Economics Rules: The Rights And Wrongs Of The Dismal Science.