Even children intuitively understand that exchange can and often does mutually benefit those who trade, says Dylan Pahman in this week’s Acton Commentary. “As it turns out, that mutual benefit is often not only material but, at its base, moral as well.”

I am unsure how it is that Rita ended up with a peanut butter and M&M sandwich in the first place. Certainly not under our current First Lady’s watch — that’s for sure. Perhaps Rita’s mother let her pack a lunch as an exercise in responsibility, and when her mom wasn’t looking Rita would sneak the red-, green-, brown-, and yellow-covered chocolates into the white bread bookends of her (until then) plain peanut butter sandwich. Or maybe her mother was an economist, and she knew that to pack her daughter a peanut butter and M&M sandwich meant effectively to give Rita her pick of any other sandwich in the classroom.

As Adam Smith (in)famously observed in The Wealth of Nations, “It is not from the benevolence of the butcher, the brewer, or the baker, that we expect our dinner, but from their regard to their own interest. We address ourselves, not to their humanity but to their self-love, and never talk to them of our own necessities but of their advantages.” Thus the question, “Do you want to trade?” And what third grader wouldn’t consider a peanut butter and M&M sandwich to be in “their own interest”?

The full text of the essay can be found here. Subscribe to the free, weekly Acton News & Commentary and other publications here.