Paul Rubin argues that our evolutionary heritage biases us against seeing larger moral communities.
Our primitive ancestors lived in a world that was essentially static; there
was little societal or technological change from one generation to the next.
This meant that our ancestors lived in a world that was zero sum — if a
particular gain happened to one group of humans, it came at the expense of
This is the world our minds evolved to understand. To this day, we often see
the gain of some people and assume it has come at the expense of others.
Economists have argued for more than two centuries that voluntary trade, whether
domestic or international, is positive sum: it benefits both parties, or else
the exchange wouldn’t occur. Economists have also long argued that the economics
of immigration — immigrants coming here to exchange their labor for money that
they then exchange for the products of other people’s labor — is positive sum.
Yet our evolutionary intuition is that, because foreign workers gain from trade
and immigrant workers gain from joining the U.S. economy, native-born workers