Johnson argues that most countries that are now rich (a list that mysteriously but conveniently excludes Hong Kong) were once highly protectionist. Even if that's true, it doesn't really prove anything since pretty much every country, including miserably poor ones, was once highly protectionist. It's also true that all rich countries have names composed of vowels and consonants but I don't think there's a causal link.

To make his case, Johnson would have to compare countries in the past and show that the ones with more protectionism were likelier to become rich than the ones with less protectionism. I think it's extremely unlikely that he can do this.

He'd have a much easier case to make if he conceded that there is such a thing as bad protectionism (as practiced by, say, African kleptocrats) and only tried to make the case that "good protectionism" is helpful. Even here, he would have an uphill battle because he would have to establish (1) that the countries in question had an overall high level of protectionism, as opposed to having a great deal of open trade with protectionism concentrated in a few highly visible areas, and (2) that less successful countries had a lower overall level of protectionism, as opposed to their protectionism just being noticed less because they are less successful. Also, it would be helpful to know when protectionism stops being a good thing. Great Britain and the U.S. didn't stop "getting rich" in 1840 and 1940 respectively, and their subsequent openness to trade seems to have been a big part of their increasing wealth.

Here's a much more modest claim he could make, which I do think is supported by the evidence: A certain amount of protectionism doesn't need to be disastrous. All of the countries that are currently rich were once protectionist, in some cases highly protectionist, and that didn't keep them from becoming rich. When giving advice to protectionist poor countries, we shouldn't automatically assume that reducing tariff and non-tariff barriers is the best first step in economic reform.

One more thing: what Johnson says about protectionism isn't some bold new theory. It was the conventional wisdom in the early post-WW2 period. When they became independent, most ex-colonies adopted the then-fashionable policies of import substitution and protecting infant industries. The fact that most of these countries went on to do badly led to a new conventional wisdom in favour of open trade.

There are a lot of problems with letting the government decide which industries are strategic. The government can easily be seduced by the desire for success in prestige industries (a nice shiny new steel mill, a domestic car industry) rather than in the more boring industries where the country may have an actual comparative advantage. Even an honest and competent government can have this problem. And governments aren't all honest and competent. If the government is the source of fundamental business decisions, the opportunities for large and petty corruption multiply.

On one hand, the post-colonial experience argues pretty strongly against Johnson's position. On the other hand, it also argues for humility when pushing the conventional wisdom of the day on large, poor, distant countries.