My economics background is pretty formal and I’ve found that academic economists are very careful about how they use “efficiency” when it comes to markets.
Modern (in the last 100 years or so) economists don’t spend much time talking about Smith’s “invisible hand”. Instead they tend to use very precise definitions of efficiency and take great care to use them in the right place.
When economists say that “markets are efficient” they’re usually talking about the very specific case of “Pareto efficiency”, which is pretty far removed from non-economists think about when they hear “efficient”. Pareto efficient just means that we’re in a state where nobody’s situation could be improved without degrading at least one other persons situation. That’s trivially (trivial is academic speak for "it’s true but it’s so dumb it’s not really interesting) satisfied by giving all of society’s resources to a single person. Pareto efficiency specifically leaves out any concept of just how good the overall situation is. It makes no comment on how good an economy is for society overall.
Economists also have a concept called “market efficiency hypothesis”. It’s generally talked about in 3 forms; weak, semi-strong, and strong.
“Weak market efficiency hypothesis” states that all information from past stock prices is instantly reflected in current stock prices. The strongest evidence for that is that nobody has been able to create a stock picking algorithm based only on past prices that reliably makes money. If weak form weren’t true, everyone would make a killing and that’s not even possible.
“Semi-strong market efficiency hypothesis” states that all publicly available information is instantly incorporated into stock prices. The evidence for this one is shaky, at best and economists don’t pretend otherwise. If this is true, legitimate stock analysts wouldn’t be able to make money. We know that some of them do make (insane amounts of) money. The only experiments that test this suggest that those traders just got lucky.
“Strong market efficiency hypothesis” states that all private and public information is instantly incorporated into stock prices. Economists know this is false. If it were true, insider trading wouldn’t be possible and we know it happens.
So on to the more nuanced view of efficiency. People have some cost to switching houses; it’s a combination of easily measured costs like inspections, cleaning fees, moving expenses, etc as well as less easily measured costs, such as finding new friends, taking the time to learn the new neighborhood, etc. A landlord can certainly raise rent some amount over construction costs. If people have the option of moving to a place that is priced at construction cost, they will do so when the extra cost gets too annoying for them. That’s the beauty if this system, neither you, I, nor the landlord need to have a say in what the level is, the resident themselves gets to decide. We just need to make sure that they are actually able to make that decision freely and providing an indefinite stream of at-cost housing does exactly that.
My economics background is pretty formal and I’ve found that academic economists are very careful about how they use “efficiency” when it comes to markets.
Modern (in the last 100 years or so) economists don’t spend much time talking about Smith’s “invisible hand”. Instead they tend to use very precise definitions of efficiency and take great care to use them in the right place.
When economists say that “markets are efficient” they’re usually talking about the very specific case of “Pareto efficiency”, which is pretty far removed from non-economists think about when they hear “efficient”. Pareto efficient just means that we’re in a state where nobody’s situation could be improved without degrading at least one other persons situation. That’s trivially (trivial is academic speak for "it’s true but it’s so dumb it’s not really interesting) satisfied by giving all of society’s resources to a single person. Pareto efficiency specifically leaves out any concept of just how good the overall situation is. It makes no comment on how good an economy is for society overall.
Economists also have a concept called “market efficiency hypothesis”. It’s generally talked about in 3 forms; weak, semi-strong, and strong.
“Weak market efficiency hypothesis” states that all information from past stock prices is instantly reflected in current stock prices. The strongest evidence for that is that nobody has been able to create a stock picking algorithm based only on past prices that reliably makes money. If weak form weren’t true, everyone would make a killing and that’s not even possible.
“Semi-strong market efficiency hypothesis” states that all publicly available information is instantly incorporated into stock prices. The evidence for this one is shaky, at best and economists don’t pretend otherwise. If this is true, legitimate stock analysts wouldn’t be able to make money. We know that some of them do make (insane amounts of) money. The only experiments that test this suggest that those traders just got lucky.
“Strong market efficiency hypothesis” states that all private and public information is instantly incorporated into stock prices. Economists know this is false. If it were true, insider trading wouldn’t be possible and we know it happens.
So on to the more nuanced view of efficiency. People have some cost to switching houses; it’s a combination of easily measured costs like inspections, cleaning fees, moving expenses, etc as well as less easily measured costs, such as finding new friends, taking the time to learn the new neighborhood, etc. A landlord can certainly raise rent some amount over construction costs. If people have the option of moving to a place that is priced at construction cost, they will do so when the extra cost gets too annoying for them. That’s the beauty if this system, neither you, I, nor the landlord need to have a say in what the level is, the resident themselves gets to decide. We just need to make sure that they are actually able to make that decision freely and providing an indefinite stream of at-cost housing does exactly that.