What you need to keep in mind, is that there are 2 kinds of loans, which the modern world has mixed-up and no longer distinguishes between.

Productive loans
and
Un-productive loans

If I loan a man $5,000 to help buy factory equipment, I deserve to be paid interest -- a share of the profits -- because that $5,000 is going to be turned into a machine which can make widgets. That $5,000 is being put to work to make money. Those widgets are worth money. This is a productive loan.

If I loan a family man $100,000 to buy a house for his family to live in, that money is NOT working to make money. It is an un-productive loan. That house just sits there and keeps the man and his family out of the weather. That man is not using the house to make money, so why should I demand more money than I lent him? I have no claim on his other money, anything beyond the $100,000 I lent him. To demand interest on an UN-PRODUCTIVE loan (such as this case) would be usury. I am preying on his desperation for a home, and the fact that he can't afford one otherwise.

The same goes for automobile loans -- unless it's a taxi driver borrowing to buy a new taxi. But few people make money with their car. For most, it's an EXPENSE, a liability, part of the cost of living.

Whenever the interest comes "out of someone's hide" rather than out of the profits they're directly making with that money -- it's Usury.

That goes for Student Loans too. Borrowing money for eduction is an un-productive loan. I know you're making yourself more "marketable" from an employment prospective. But that money you're going to earn is going to be EARNED by working hours in a skilled/educated profession. If this weren't true, then you could get hurt and STILL draw money because of your degree. If people are paying you because of your degree, then they would pay you regardless of whether or not you do any work.

So as you see, the degree itself doesn't make money. It might help you reach a higher potential as far as income, but it's still YOU doing the work and earning money, which is rightfully yours to keep.

So getting interest on a Student Loan is also usury. Same for credit cards. People aren't charging business equipment to make money -- they're charging clothes, toys, household goods, appliances, car repairs, utility bills, food, vacations, and other personal stuff -- all of which are expenses/liabilities.

All interest is Usury!

You comparing things in Jesuitical thoughts.

If a Man wanted to borrow $5,000 for his business, give him the $5000 for XX% of his company ownership.  If you truly believe it is going to be a successful business then being a part owner is the most profitable for both parties.

Or give him the $5,000 and agreed upon a lump sum due date that is reasonable.  Like in 3 years he will pay you $6,500 all at once.

What you need to keep in mind, is that there are 2 kinds of loans, which the modern world has mixed-up and no longer distinguishes between.

Productive loans
and
Un-productive loans

If I loan a man $5,000 to help buy factory equipment, I deserve to be paid interest -- a share of the profits -- because that $5,000 is going to be turned into a machine which can make widgets. That $5,000 is being put to work to make money. Those widgets are worth money. This is a productive loan.

Unless the endeavor fails. Then the loan is decidedly unproductive.

If I loan a family man $100,000 to buy a house for his family to live in, that money is NOT working to make money. It is an un-productive loan.

That house just sits there and keeps the man and his family out of the weather.

This makes it sound like there is no value in keeping the man and his family warm and dry.

That man is not using the house to make money, so why should I demand more money than I lent him?

This statement is my main reason for replying, so I'd very much like to argue this point above all others.

Because if he doesn't give someone, anyone, more money than they lent him, why exactly would anyone lend him anything??

This would limit lenders to one's family (at best) or simply no one.

And what of the risk the lender takes that he'll not be paid back?? Interest is a function of risk among other things.

I have no claim on his other money, anything beyond the $100,000 I lent him.

And no one loans him money. Ever. Why would they?

To demand interest on an UN-PRODUCTIVE loan (such as this case) would be usury.

or, it could be mutually beneficial . Lender makes a few bucks, guy gets a house (over time, he owns that house.

I am preying on his desperation for a home, and the fact that he can't afford one otherwise.

Desperation? Or just desire. A working shmoe can see renting is often lame. I presume you'd propose lifelong tenancy? Or just save up until you can buy some acres and a mule your own then fell some trees on your new land, adze them, and build a cabin?

The same goes for automobile loans -- unless it's a taxi driver borrowing to buy a new taxi. But few people make money with their car. For most, it's an EXPENSE, a liability, part of the cost of living.

a way to commute to work? No needing to rely on the job market of the town where you choose to live? A way to work where the jobs are (traffic congested hellholes) and live in a place you'd actually feel your kids were safe(r) (a suburb or even a rural area). Cars are also probably the cheapest way to take a vacation, even to go camp, for a family.

Whenever the interest comes "out of someone's hide" rather than out of the profits they're directly making with that money -- it's Usury.

it's "out of someone's income," not their hide. We've no debtor's prisons.

That goes for Student Loans too. Borrowing money for eduction is an un-productive loan. I know you're making yourself more "marketable" from an employment prospective.

no, "marketable" is for jobs where candidates need to market themselves. Certain jobs need no marketing, just the credentials (e.g. engineering, certain technology jobs, medicine) and you can't "work your way up the ladder" from janitor to doctor, you'll need an MD at some point. Same with engineering: most states require a bachelor's, you can't just take the PE and get a license.
An education can absolutely be an **investment**

Take those loans to study the finer points of Aquinas, however, good luck with that.

But that money you're going to earn is going to be EARNED by working hours in a skilled/educated profession

as is the money earned running the business you seem willing to loan to.  Either way you're paying back the loan by "mortgaging" future income streams, whether earned from salary as an employee or accounts receivable as a business owner, this is more a tax structure question than a meaningful distinction between how the money is earned.

. If this weren't true, then you could get hurt and STILL draw money because of your degree. If people are paying you because of your degree, then they would pay you regardless of whether or not you do any work.

and a business can fail.
They can sell buggy whips after everyone started driving cars, be in the wrong location, do poor work, or, yes, get hurt and be unable to run the business like the tree surgeon I knew.

So as you see, the degree itself doesn't make money. It might help you reach a higher potential as far as income, but it's still YOU doing the work and earning money,

you continue to make it sound like a business owner only need hang out a shingle and sit by his fax machine for POs, which presumably his customers will pay when he delivers no good or service. A business does not, by its very existence produce money.

So getting interest on a Student Loan is also usury

same argument as above, take away the interest, no one will loan to students. Only those with family money or rich benefactors will go to college. Go ahead and talk about the golden years when people worked their way through college, when college was vastly cheaper (baby boomer years) due to serious subsidies, or before that look at who got a college education, the already privileged and the very, very, very talented, and Charles Dickens' Pip.

. Same for credit cards.

Take away the interest and there go credit cards. They'll vanish. And while you might think that's a good thing, I like having an emergency way to pay for unforeseen expenses, to "float" them a month or so.

Just because some (most) use credit cards irresponsibly, doesn't mean I want them gone. Like guns, I have them, I use them, some can't handle them doesn't mean mine should be taken away.

People aren't charging business equipment to make money -- they're charging clothes, toys, household goods, appliances, car repairs, utility bills, food, vacations, and other personal stuff -- all of which are expenses/liabilities.

Yep, see above.

if you have a savings account you are charging the bank interest. Is that sinful?

If this is a main reason for having a savings account and there is no other way to entrust your money.

St. Thomas discusses "saving's accounts" in Summa II-II q. 79 a. 4 ad 3:

If one were to entrust one's money to a usurer lacking other means of practising usury; or with the intention of making a greater profit from his money by reason of the usury, one would be giving a sinner matter for sin, so that one would be a participator in his guilt. If, on the other hand, the usurer to whom one entrusts one's money has other means of practising usury, there is no sin in entrusting it to him that it may be in safer keeping, since this is to use a sinner for a good purpose.