"A core proposition in economics is that voluntary exchanges benefit both parties. We show that people often deny the mutually beneficial nature of exchange, in

"A core proposition in economics is that voluntary exchanges benefit both parties. We show that people often deny the mutually beneficial nature of exchange, instead using zero-sum thinking." If one doesn't fully conceive of trade as value-for-value as a principle, there are many other human interactions and relations one will perceive in a completely distorted fashion.