Debt is treated as a single thing — either you are in it or you are not, either it is virtuous to avoid it or foolish to fear it. The truth is that there is a clean line running through the middle of all debt, and which side of it you are on matters far more than the amount.
Ask people what they think about debt and you will usually get one of two reflexes. One camp treats all debt as a moral failing, a trap to be avoided at any cost. The other treats it as a tool the wealthy use freely, and the timid avoid to their loss. Both are half right, and being half right about debt is an expensive place to stand — because the question was never whether debt is good or bad. It is which kind you are holding.
There is a line that runs through all borrowing, and it has nothing to do with how much you owe or how it feels. It has to do with one thing: what the borrowed money does once you have it.
The line, drawn plainly
Here is the distinction in a single sentence. Good debt is borrowing to acquire something that is expected to grow in value or generate income over time. Bad debt is borrowing to acquire something that loses value or simply disappears in consumption.
That is the whole test, and it is mechanical, not moral. Borrow to buy an asset that earns or appreciates, and the debt is working alongside you — the thing you bought can help pay for itself, and may be worth more later than it cost. Borrow to buy something that depreciates or is consumed, and the debt outlives the value it bought. You are left making payments, with interest, on something that is already gone or worth less than you paid.
The classic examples make it concrete. Borrowing to fund an education or a productive business is, in principle, borrowing against future earning power — the debt buys something that can generate income to repay it. Borrowing at high interest to fund everyday consumption — a financed lifestyle, an expensive depreciating purchase put on credit — is the opposite: the pleasure fades, the balance compounds, and you pay for years for something that returned nothing.
Why the interest rate decides the severity
The growth-versus-consumption line tells you the kind of debt. A second factor tells you how dangerous it is: the interest rate, working through compounding.
Recall how compounding behaves. On a high interest rate, unpaid balances don’t grow in a straight line — they accelerate, because each period’s interest enlarges the base the next period’s interest is charged on. This is why high-interest consumer debt is the most destructive financial position an ordinary household can hold: it combines the worst kind of debt (funding things that don’t grow) with the most aggressive version of the mechanism (a rate high enough to compound viciously against you).
Low-interest debt against an appreciating asset and high-interest debt against vanished consumption are not two points on the same scale. They are nearly opposite financial events that happen to share the word “debt.” Treating them as the same thing — being equally proud of avoiding both, or equally relaxed about carrying both — is the core mistake.
Why “all debt is bad” quietly costs you
The instinct to avoid all debt feels safe, and for high-interest consumer debt it is exactly right. But applied universally, it has a hidden cost, and that cost is the mirror image of the Cantillon and compounding lessons.
If good debt lets you acquire an income-producing or appreciating asset earlier than you otherwise could, then refusing all debt on principle can mean standing still while the asset — and its returns — runs ahead of you. The person who waits to buy the productive thing in cash may pay a different price: the years of growth they sat out. This is not an argument for borrowing recklessly. It is an argument that a blanket rule, in either direction, replaces thinking with a slogan — and slogans are not how the people who use debt well actually decide.
What this is not
This is not advice to take on any particular debt, or to avoid any particular debt — your rate, your stability of income, and what you are buying all matter, and no general article can weigh them for you. It is not a claim that “good debt” is risk-free; borrowing against an asset that then falls in value is its own danger. It is one durable distinction, offered so you stop asking the useless question — is debt bad? — and start asking the useful one.
The question to keep
So the next time you are about to borrow — or feel virtuous about refusing to — skip the moral reflex and run the mechanical test:
Is this money buying something that will grow or earn, or something that will shrink or vanish? And at this interest rate, is compounding going to work alongside me, or quietly against me?
We are not here to tell you to borrow or to abstain. We are here to make sure you can see the line that runs through all debt — because which side of it you stand on decides far more than the size of the number ever will.
Blind Insights — clarity on money, the economy, and power. We look beneath the surface, because that is usually where the answer is. More at blindinsights.de