Argentina is collapsing. Its economy wasn't great before, but austerity is destroying its own foundation for short-term profits for the wealthy. See again: Sowell purely works for the obscenely wealthy against the needs of the people.

As for Africa, it is not Socialism that keeps the various African nations under-developed. Like Parenti said, they aren't under-developed at all, really, they are over-exploited. Imperialism from the Global North has carved out of Africa and South America the lion's share of their resources:

But that expropriation of the Third World—has been going on for 400 years—brings us to another revelation—namely, that the Third World is not poor. You don't go to poor countries to make money. There are very few poor countries in this world. Most countries are rich! The Philippines are rich! Brazil is rich! Mexico is rich! Chile is rich—only the people are poor. But there's billions to be made there, to be carved out, and to be taken—there's been billions for 400 years! The Capitalist European and North American powers have carved out and taken the timber, the flax, the hemp, the cocoa, the rum, the tin, the copper, the iron, the rubber, the bauxite, the slaves, and the cheap labour. They have taken out of these countries—these countries are not underdeveloped—they're overexploited!

Please, elaborate on what you think Socialism is, if it is keeping African nations under-developed.

No, economy is not a zero-sum game, correct. However, one has to call into question the purpose of a system that is built to make a few people obscenely wealthy on the backs of the vast majority. Capitalism naturally suppresses the wages and material conditions of workers, whose conditions gradually, microscopically improve, or even deteriorate, while Capital concentrates in fewer and fewer hands. The end result of Capitalism is monopoly. Once a hypothesis, this statement is now a confirmed fact.

I'm aware of Sowell's past as a "Marxist." Many people have donned such a moniker and failed to genuinely grasp Marxism, and the existence of one such fellow-turned crank does not at all lend credibility to Sowell. Marxism does not turn to dictatorship, rather the vast majority of AES states represented vast democratization of the economy, from Cuba (previously a country of fascist slavers) to Russia (under the thumb of the Tsar) to China (under the thumb of the Nationalist Kuomintang) to Vietnam (under the thumb of colonialist France) and more.

I've read enough of Basic Economics to know that Sowell is a crank. I haven't read it cover to cover, nor do I care to waste my time studying every crank in the world of economics in-depth. I don't imagine you've read Marx's works much either, nor do I expect you to, you clearly have chosen the side of Sowell and the microscopic few that profit off of the vast majority of the population via extortion.