For all the doubters, I challenge you to show me an example of a simple economy (you should need just a few people and a few transactions to prove the point) where the following is not true:
(price of 1 BTC) >= [(World GDP in dollars)*(fraction of economic transactions using bitcoin)]/[(supply of bitcoins)*(fraction of bitcoins used in transactions)*(bitcoin velocity)]
...I will be very impressed if anyone is able to do it.
You can not show such a thing, that formula is an example of something that is not refutable.
It's an identity, stemming from the definition of velocity. So the equality does hold. The question seems to be whether it's useful or not.
The only thing that is measurable in that formula is the supply of bitcoins, maybe not even that, because we can never know how many is saved, and we can not know the volume of credit.
The non-measurability claim seems weird to me. Maybe some of these things are hard to measure, and we need to estimate them, but clearly in principle we can measure them.
Here's a simple economy for one year: Frank starts with 3 fish and 1 BTC, Paul starts with 2 peppers and 2 BTC, Carl starts with 4 cows and 3 BTC.
Frank sells two fish to Paul for one BTC. Carl sells one cow to Paul for one BTC. Paul sells one pepper to Carl for one BTC.
We can calculate every term in MV = PT in the above scenario. Is your objection just that these things are hard to measure in real life?
The velocity of money is just stupid, it can not be measured, and if it could, why should it affect the bitcoin value?
Let's pretend we look into a crystal ball to see the year 2020, and we know M (19 million BTC), we know V, because you're assuming we know V, and we know GDP because some economists will have calculated it the same way they do today. Then we can use the MV=PT identity to infer the price of a bitcoin! That's pretty amazing. Without that identity, we couldn't do it. We both agree the identity is true/axiomatic. We've just used it to learn something, assuming we can estimate V.
This article by Frank Shostak (with citations from Mises and Rothbard) is very readable and explains it far better than I can:
http://mises.org/daily/918I unfortunately did not find the article very convincing. The author and Mises/Rothbard kept asserting things that didn't follow from their premises. The best example is "since velocity is not an independent entity, it as such causes nothing and hence cannot offset effects from money supply growth."
Some other quotes:
"The number of times money changed hands has no relevance whatsoever on the baker's capability to fund the purchase of potatoes."
Agree, but not relevant.
"Observe that, since bread, potatoes, and sugar are not commensurable, no average price of money can be established. "
They were shown to be comparable since they all have a certain price in terms of money, and thus by extension with each other.
"The peculiarity of these prices lies merely in the fact that they cannot be expressed in terms of money."
The price of anything can be expressed in relation to anything else.
I find the writing of Mises and Rothbard unclear (in comparison to someone like Milton Friedman), so it's possible I'm not understanding them.