I would argue that there is not enough homogeneity in the world yet to formulated a general case theory of trade that fits the diversity of facts enough to be useful as a policy tool.
Another problem that is seldom acknowledged is asymmetry of power. Nations are assumed to pursue their own national interest and asymmetrical power allows powerful nations to achieve their interest at the expense of other nations if they so chose and there is a lot of social, political, and economic pressure domestically to do so.
As a result modeling international trade in terms of universally applicable principles is often more a matter of rhetoric (persuasion) rather than evidence-based reasoning (science).
Here I think the Chinese principle of social harmony is the wiser choice that the liberal principle of individual preference and and pursuit of interest "because freedom."
International conflict almost always has a strong economic component if not a foundational one. That was true historically under mercantilism, and it has changed much since abandoning the metals. Political power generates economic power, and economic power conditions political power.
Humans are territorial animals. We need to talk about this instead of assuming that an invisible hand will right the scales in a liberal world order of "free trade" and floating exchange rates.
In the fist place, there is no really free trade owing to all the artificial boundaries that are imposed legally. This is what the recent trade agreements were really all about (TPP, TTIP and TiSA). The "free" was just rhetoric to persuade.
The "free" in "free trade" means free of government intrusion, which implies loss of national sovereignty to global forces and institutions. This predictably leads to a global technocratic plutocracy ruled by transnational corporations and oligarchs.
Workers in all countries get the short end of the stick, even though "everyone is better off" statistically looking at aggregates.
The Case for Concerted ActionDani Rodrik On Free Trade