A lot of things that we cannot buy and sell in markets used to be totally legal objects of market exchange - human beings when we had slavery, child labour, human organs, and so on. So there is no economic theory that actually says that you shouldn't have slavery or child labour because all these are political, ethical judgments.

In this quote, Ha-Joon Chang highlights the historical fact that many practices now considered unethical, such as slavery, child labor, and the exchange of human organs, were once legally and economically accepted. He points out that in the past, these practices were part of the market exchange, and the idea that they are now unacceptable was not derived from economic theory but from evolving political and ethical judgments. Chang's statement challenges the notion that all practices should be governed purely by market forces, emphasizing the role of moral considerations in shaping economic systems.

Chang's argument suggests that economic theory, by itself, does not dictate what is morally right or wrong. Practices like slavery and child labor were economically justified at various points in history, and it was not economic theory that eventually ended them, but the collective societal realization that these practices were immoral. This emphasizes the need for a broader ethical framework to guide economic decisions, beyond just supply, demand, and profitability.

By invoking these extreme examples, Chang makes the case that some actions cannot simply be assessed through an economic lens. Political and ethical judgments are critical in determining which practices are acceptable in society, regardless of their market value. In other words, the market does not inherently decide what is just or unjust; it is the political and ethical decisions of a society that shape those boundaries.

Ultimately, Chang's quote reflects on how the moral evolution of society influences economic practices. He argues that the shift away from accepting practices like slavery and child labor was a product of political activism and moral enlightenment, showing that economic systems are not autonomous and must be subject to the moral and ethical values of the people.