At its most basic level, reciprocity is about giving what you get. It’s about treating someone in kind — if they treat you well, treat them well in return. It’s one of the most basic laws of social psychology, to provide equal benefits to someone who helps you in some way.

The concept of reciprocity is found again and again as a theme within ethics, and as a moral principle shared by religions and cultures around the world, and through the ages.

The Golden Rule

Perhaps the most famous rendition of the concept of reciprocity is in the philosophy of the Golden Rule: “Do unto others as you would have them do to you.” The aphorism “you scratch my back, I’ll scratch yours” is a folk wisdom variation on the theme as well.

The idea stretches all the way back to ancient Egypt, and appears in Judaism, Zoroastrianism, Buddhism, Daoism, Catholicism, Hinduism, during Confucius’ time circa 551 BCE, in Islam, and has been found in some form in most of the world’s major philosophies and religions through the centuries.

The Greatest Commandment

Jesus was a big believer in reciprocity — his Greatest Commandment was to love thy neighbor as one loves thyself. During the important Sermon on the Mount speech he named it as the very highest pinnacle of his instructions for followers and believers here on earth.

The moral bedrock of Christianity is embedded in the concept of reciprocity.

Game Theory

This branch of decision science studies how people and groups may respond to each other in interactive games — as a model for the “game of life.” The collection of game theory models formalize a set of logical probabilities for behaviors and outcomes based on statistical data from performed experimentation in playing the games. It’s a field where economic theory meets mathematics meets probability meets human psychology and group behavior.

Reciprocity is a useful principle for exploring using game theory. It’s a relatively simple rule that can determine the probabilistic actions of various agents given decision-making criteria. Some of these formalized models include the following:

• Tit-for-tat
• Prisoner’s Dilemma
• Zero-sum

Business

Reciprocity is a useful and frequent concept in the business world as well. In many ways it forms the basis of all contracts — the basis of the legal philosophy that underpins the very concept of contracts.

Some figures worth exploring further on this topic:

• Dale Carnegie
• Nassim Taleb

Related concepts

• Use in diplomacy — JFK‘s 1963 speech about sending National Guardsmen into Alabama to help admit 2 Black students to the University of Alabama
• Evolutionary biology — reciprocal altruism (similar to tit-for-tat in game theory)
• deontological ethics
• Kant
• Buddhism — because there is no revealed wisdom in Buddhist beliefs, there is a fundamental egalitarianism and requirement of reciprocity to participate materially in related religious groups
• Confucianism — Confucius’ disciple asked, ‘Is there any one word that could guide a person throughout life?’ The Master replied: ‘How about shu: never impose on others what you would not choose for yourself?’