[Editor’s Note: The following is a guest post by Jonathan Anomaly, assistant professor of political science at Duke University.]

When we look around the world and observe the massive wealth disparities between citizens in rich and poor countries, many of us are apt to conclude that the differences must have arisen because of colonialism, imperial warfare, or theft of raw materials like gold or oil. Of course, all of these things have happened at various points in time, and they can arguably explain some variation in the standard of living. Colonialism can be especially destructive of institutions that support peace and commerce. But a recent article by the philosopher Dan Moller casts doubt on the view that injustices like these can explain much of the observable differences.

Instead, Moller musters economic data to suggest that blatant injustices barely show up in the overall trajectory of economic growth in most countries over long periods of time. Specifically, Moller appeals to “the Great Divergence,” illustrated by graphs like this. The basic idea is that rich countries got rich by pulling away from poor countries, not by making other countries poor.

Not surprisingly for economists, the main explanation for the Great Divergence is trade, fostered in part by favorable cultural and political institutions. This may seem obvious to those who understand that trade is a positive sum game, and that there are exponential gains from trade as markets expand and the division of labor becomes more fine-grained. The problem is that most philosophers who write about global poverty are convinced otherwise. They think that people in wealthy countries are in some sense responsible for poverty in less developed countries, and that we therefore have an obligation to do something about it.

So, who’s right? Moller thinks that if citizens in wealthy countries did not cause poverty among citizens in other countries, we are not violating any obvious moral duties by failing to offer aid.

Moller’s main argument is that if we get rich because of good political institutions, or because we live in a culture that encourages social and scientific experimentation, we are not doing wrong to others – even if none of us can take credit for the contributions or our ancestors. When people in one country create the conditions for endogenous economic growth they do not thereby cause people in other countries to fail to do so. If anything, over the long run, one country’s success makes it more likely that other countries will follow suit.

By analogy, suppose a family in a nearby community is not doing as well as we are, and that we know exactly what resources they need to improve their prospects – cash, a new car, or extra math tutoring. It is not obvious that by failing to provide these things for them, we are morally responsible for their relative poverty. To extend the analogy, if people in our neighborhood are wealthy mainly because we have a well-functioning Neighborhood Association and a robust trading network, our relative success is not causing people in nearby neighborhoods to fare worse than we are.

This is not to say we shouldn’t help people in need, especially when we have a reasonably good idea of how to do so, or when we have committed an injustice against them in the past. It’s just to say that massive wealth disparities are not always caused by injustice.