Justin Nakamoto-San ☑️ on Nostr: another great reference: St. Thomas Aquinas (1225–1274 CE) – Building on ...

another great reference:

St. Thomas Aquinas (1225–1274 CE) – Building on Aristotle, Aquinas argued in Summa Theologica that usury is sinful because money is only a medium of exchange and should not be sold for profit.

Aquinas' critique of usury in Summa Theologica (II-II, Question 78) is based on his broader philosophical and theological principles. Here’s a deeper analysis of the passage:

1. Usury as "Selling What Does Not Exist"

Aquinas argues that charging interest on a loan is unjust because it involves selling something that does not actually exist. Money, in his view, is merely a medium of exchange with no intrinsic productive capacity. Unlike land, labor, or goods, which can generate value, money itself does not "grow" or reproduce naturally.

By charging interest, a lender essentially sells the use of money separately from the money itself—despite the fact that the borrower must return the original sum. Aquinas sees this as "double-charging" and therefore unjust.

2. The Principle of Justice and Equality

Aquinas links usury to justice, particularly commutative justice, which governs fair exchanges. If a person lends money and then demands more in return without any additional exchange of goods or services, it creates an inequality in the transaction. This violates the natural moral order, which should ensure fairness in economic dealings.

3. The Distinction Between Consumable and Non-Consumable Goods

Aquinas makes a distinction between:

Consumable goods (e.g., wine, grain, or money): When you use them, they are "used up." Lending such things means transferring their ownership, and charging extra for their use is unjust.

Non-consumable goods (e.g., houses, tools, land): These can be rented out legitimately because the borrower can use them without consuming them.


Since money is a consumable good (it is spent when used), Aquinas argues that charging rent (interest) for its use is unnatural.

4. Exceptions and Practical Considerations

Although Aquinas condemns usury in principle, he acknowledges some exceptions:

Damnum emergens (compensation for loss) – If a lender suffers a real financial loss due to a delayed repayment, some form of compensation may be justified.

Lucrum cessans (loss of potential profit) – If a lender forgoes a legitimate business opportunity by lending money, some interest could be justified under strict conditions.

Mutuum (interest-free loans as charity) – Aquinas encourages interest-free lending as a Christian duty, particularly to help the poor.


5. Influence and Legacy

Aquinas' arguments against usury influenced medieval Christian doctrine, shaping the policies of the Catholic Church and later Protestant thinkers. His views contributed to the long-standing prohibition of usury in Christian Europe, leading to alternative financial structures such as:

Jewish moneylenders (who, due to different religious laws, often became key financial figures in medieval Europe).

Islamic finance, which still prohibits riba (usury) today and encourages profit-sharing models instead of interest-based loans.


Comparison with Modern Economics

Today, modern economic systems largely reject Aquinas' strict prohibition on interest, arguing that:

Money has time value – Interest compensates lenders for delaying their own use of money.

Risk justifies interest – Lenders take on a financial risk when they lend money, which interest helps to offset.

Inflation erodes value – Charging interest can compensate for the decreasing value of money over time.


However, Aquinas’ concerns about fairness and exploitation remain relevant, especially in discussions about predatory lending, payday loans, debt slavery, and financial ethics.

Would you like to explore how modern financial systems address these concerns?