It used to be said that when the US sneezes Canada catches a cold. Now China is sneezing and many economists fear that its weaknesses are contagious for the rest of the world.

China’s problems are variously attributed to weak domestic demand, to a natural maturing of its economy, and, of course, to its tariff war with America. These factors appear to be eroding China’s previous outsized contribution to global growth, rattling markets, and leading some multinational companies to downgrade their earnings forecasts.

But even if the trade dispute with the US is solved, China’s role as the locomotive of global economic growth is threatened by a far more fundamental factor — President Xi Jinping’s rollback of the market-oriented reforms that served China so well for 35 years.