conza:

“A most important truth about money now emerges from our discussion: money is a commodity. Learning this simple lesson is one of the world’s most important tasks. So often have people talked about money as something much more or less than this. Money is not an abstract unit of account, divorceable from a concrete good; it is not a useless token only good for exchanging; it is not a “claim on society”; it is not a guarantee of a fixed price level. It is simply a commodity [emphasis added]. It differs from other commodities in being demanded mainly as a medium of exchange. But aside from this, it is a commodity—and, like all commodities, it has an existing stock, it faces demands by people to buy and hold it, etc. Like all commodities, its “price”—in terms of other goods—is determined by the interaction of its total supply, or stock, and the total demand by people to buy and hold it.”

          — Murray Rothbard

Since this was tagged Bitcoin it seems fair to assume that the quote is presented with that digital currency in mind.

Bitcoin has already gotten started as a medium of exchange, that bridge has already been crossed. We need not worry about how people will transition from holding it for ‘direct use’ to holding it for trade because we’re already at a stage where a large, and growing, minority of people are already trading it.

It’s not yet widely accepted, but gaining ground quickly and there’s no obvious barrier that rules out the possibility that it eventually will be. People seek to hold it, among other reasons, because of properties that they find very desirable in a good used for exchange, and because they anticipate that in the future, increasing numbers of people will come to feel the same way.

So in a possible future in which most people buy groceries with Bitcoin, what use is Rothbard’s earnest proclamation that Bitcoin cannot be money?

Or if Rothbard’s prescriptive version of the regression theorum somehow precludes Bitcoin from ever being widely accepted, how exactly does that mechanism work?