We might not care so much about these inequities if the digital revolution were reducing the costs of all the many things the typical household wants to buy, from steak dinners to adequate housing to a top-flight university education. But cost reductions have so far been highly uneven: massive for some things, such as digital entertainment; completely absent for others, such as homes in nice neighbourhoods.

And so stagnant wages end up mattering an awful lot. Low pay for the great mass of workers is distributionally unfair. It undermines support for the market-based economic system that enables sustained economic growth. Low pay also reduces the incentive to invest in technologies that boost the productivities of less-skilled workers, or which substitute [...] it is an enormous problem; continued productivity growth is ultimately the route to lives of greater comfort for all of humanity: it is how humanity contrives to produce more from less, so that all can have more.

[...] Many of the world's richest cities are choked by inadequate infrastructure. Given rock-bottom interest rates, it seems absurd that places like New York, London and San Francisco aren't receiving extraordinary new investments in that infrastructure [...]

The rich world could shepherd the global economy towards that ideal outcome by allowing lots more immigration from poorer places. Immigration would enable richer places to 'export' their strong social capital to poorer places (by bringing large shares of the populations of poorer places into countries where strong social capital dominates). That would naturally deepen social and financial capital per human worker. Global savings could also be mobilized to invest in additional infrastructure in the rich countries accepting new workers. The appetite for safe, rich-country government debt is nearly insatiable.