Okay, let me give my theory of interest too.
In a pure market economy, the market follows the people’s preferences. If everybody stops liking one thing, and starts liking another, the first will disappear from the market no matter what, and the second will appear if it’s possible. If the average preferences move in one direction, the market tries to move in the same one. It follows their preferences.
So in the 1st thread that trulib linked to, I asked in the the PTTP, where is everything equal? If everything else is constant, people prefer present goods to future ones. But where is everything else constant? Well, I think that the answer is that it’s constant with money. As the commonly accepted medium of exchange, it can get you anything that the market has. But what if you change your preferences from one time to another? In the ice in the winter vs. ice in the summer example, you change your preference for the ice. In the winter, it’s not as useful as in the summer. In short, your preferences shift from one time to another. But in the pure market economy, the market follows your preferences! If you’re preferences change from one time to another, what your money can buy changes in proportion. The fact that the market moves cancels out the fact that your preferences move, and all that’s left is time preference. And as I said in this post, I suspect that the time preference is born out of the fact that you’re never perfectly certain that what you think are the means to your ends really are such.
But certainly the pure market economy doesn’t really follow your preferences? Doesn’t it have everybody else to take into account? Well yeah. I guess that I was just trying to make the explanation simpler. For one loan to the next, the rate of interest might be a lot different. I mean, different people have different time preferences, right? So I’m just talking about the average rate of interest or whatever. In the pure market economy, the market follows the average preferences, so the average rate of interest is where everything else is constant. So I guess that my theory of interest is a “monetary” one too? Or maybe I have no idea what that’s supposed to mean.
Anyway, in the 1st thread, I mentioned that the PTTP starts out with the statement that to act, the person must prefer present goods to future ones (because otherwise they would never do anything), but how that doesn’t lead to the idea that there are different rates of time preference. If I prefer present goods to future ones, how does that have anything to do with any sort of rate of time preference (that I might prefer 1 good sooner to 2 later, 1 sooner to 3 later, or whatever)? Well, that was a rough restatement, so make sure to refer back to the original thread, but either way the point is that I think that my idea that it’s the uncertainty that accounts for the time preference gives us the different rates. I can be more or less uncertain about a production procedure. And there are 2 variables: Uncertainty that each step will lead to each other step, and the amount of steps. If I’m 90% certain that step 1 will lead to step 2, 90% for step 2 to 3, the same for 3 to 4, and so on until 10 (the end), we have to take into account that the overall certainty decreases with each step. Somebody who knew some probability theory could probably tell you by how much. I guess.
Anyway, that’s my tentative theory of time preference and interest.