But increased unemployment is not inevitable. There is no limit to the number of service jobs that we can create in retail, restaurants and catering, hotels, and an enormous variety of personal services. Walmart, for example, employs two million people, and the U.S. Bureau of Labor Statistics forecasts that more than one million additional jobs will be created in America's leisure and hospitality sector in the next decade.
But the wages that the market will set for these jobs may result in yet greater inequality. And there is no reason to believe that politicians' all-purpose answer to the problem – "increase workforce skills" – will offset this tendency. However many people learn superior IT skills, Facebook will never need more than a few thousand employees. And access to high-paid jobs is likely to be determined not by absolute skill level, but by relative skill in a winner-take-all world.
At least, however, IT products and services are very cheap, so even the relatively poor can afford them. That might make very unequal societies more stable than many fear. In his recent book Average is Over, the economist Tyler Cowen makes the deliberately provocative argument that while new technology will produce extreme inequality, the relative losers, satiated by computer games and Internet entertainment, and provided with the basics of a minimally acceptable life, will be too docile to revolt.
(Read more: Income inequality: Is it good for everyone?)
Cowen may be right; the poor may not rebel. But extreme inequality should still concern us. Beyond a certain point, unequal outcomes inevitably fuel greater inequality of opportunity; and extreme inequality of either outcomes or opportunity can undermine the idea that we should all be equal as citizens, if not in material standard of living.
So Pope Francis was right: despite capitalism's undoubted success as a system for generating economic growth, we cannot rely on market forces alone to generate desirable social outcomes. All new technologies create opportunities, but free markets will distribute the fruits of some new technologies in dramatically unequal ways. Offsetting such outcomes will be a greater challenge today than it has been in the past.