Book 5 / Chapter 4
Paragraph 2 - The Concept of Just Exchange
Explanation - Part By Part
"These names, both loss and gain, have come from voluntary exchange; for to have more than one's own is called gaining, and to have less than one's original share is called losing, e.g. in buying and selling and in all other matters in which the law has left people free to make their own terms;"
Aristotle is emphasizing how the ideas of "loss" and "gain" come about in situations where people freely trade or exchange goods and services. In such voluntary exchanges—like buying and selling—the person who ends up with more than what was initially theirs is said to have "gained," while the person with less than what they originally had is understood to have "lost." These terms arise in contexts where individuals are allowed by law to decide the terms of their exchange, meaning there’s no outside authority dictating how the transaction should happen.
"but when they get neither more nor less but just what belongs to themselves, they say that they have their own and that they neither lose nor gain."
This part is essentially about fairness and balance in transactions or dealings between people. When individuals end up with exactly what is rightfully theirs—no more and no less—they consider the outcome fair and just. In this case, they neither feel like they've gained something extra (unfair benefit) nor lost anything that was rightfully theirs. It’s about maintaining equilibrium—having what “belongs to themselves” ensures a sense of fairness and avoids inequality.
"Therefore the just is intermediate between a sort of gain and a sort of loss, viz. those which are involuntary;"
Aristotle is focusing on a specific kind of justice here, referred to as rectificatory justice. This type of justice applies to situations where someone gains something they shouldn't have, or someone loses something they shouldn't have, typically through wrongdoing, whether intentional or accidental (what he calls "involuntary" interactions). Justice, in this sense, aims to restore balance or fairness by bringing the parties back to an equal footing—neither having gained unfairly, nor having suffered an undue loss. This idea of being "intermediate" captures the essence of justice as the fair midpoint between extremes of excess (gain) and deficit (loss).
"it consists in having an equal amount before and after the transaction."
Aristotle is explaining here that justice, when it comes to exchanges and transactions, means fairness, or maintaining balance. In simple terms, if two people enter into a transaction—whether it's a trade, a sale, or any kind of agreement—justice is achieved when each person ends up with an equal and fair share after the exchange. No one should unfairly "gain" at someone else's expense, nor should anyone suffer a "loss" that leaves them with less than they deserve. Justice in this context ensures that what people have afterward is proportional to what they contributed or agreed upon at the start.
In essence, justice in transactions is about keeping things balanced and making sure everyone walks away with what rightfully belongs to them, no more and no less.