Dear Robert,

Thank you for your comments.

I think the problem is many folds. My still naive look into the matter suggests to me the following.

There are two sides to the "problem of money" and its relation to economics.
First, there's the domain of reality. 1. What objects do people call money (or monies)? 2. What acts do they perform when they engage in monetary transactions? 

Then, there's the domain of observation and explanation. 1. What do observers call money (or monies)? That's where Locke comes in with the "weight of silver," if I'm not mistaken. 2. How does the use of money affect the larger system, the economy, far beyond, and individual transactions?

Of course, the domain of reality and that of observation and explanation are interrelated, but I don't think they can be reduced from one to the other.

At a Ph.D. stage, we aren't allowed much space to "have opinions." But, it seems to me that "what people do" and "what economists think people do" are often at odds... and much of it comes down to what we (economists) think money is, how it "behaves", etc. That's why I'm insisting on the effects of the "concept of money" on one's broader theoretical taking on the economy. 

Anna Schwartz and Milton Friedman (1970) offer a good example: "The problem of the definition has received much attention - in our opinion far more than it deserves.". As a policy, monetarism fell from grace rather quickly, but some of its underpinnings remain in much macroeconomic thinking.

Now that I've beaten around the bush, I'd like to reply directly to Robert's comments.

I fail to see how "trust" in the sense that I've used departs from that of Locke and Womack. Sociologically, money "shifts the source of trust". In moneyless economies, economic coordination requires much trust in community members. In monied economies, it's not that we no longer trust the community members, but we must also trust that the monetary unit will be passed along. The "introduction" of money in society - with many of the developments of other market characteristics - entails the need to trust the monetary system, which may lead to less trust being placed in the community.

Here, I'd like to make complicate matters a bit. Everything that I've argued, I've done so with capitalism in mind. I can't comment on ancient civilizations such as those Robert mentioned. My comment regarding the anthropologist was just a reminder of the often unrealistic assumptions we make when discussing the origins of money, what Schumpeter called the logical and historical origins of money.

To cap off. I'm not entirely sure how useful the "discovery of the (many) origins of money" or "how ancient civilizations used quasi-monies" can be to modern economics. (Robert, I'm in debt to you, I haven't replied to your e-mail on Prof. Hoover's WP, but I plan to do so, I may find the relevance I've just said I haven't found yet). Ganssmann (2012) asked if we shouldn't keep the word "money" to modern societies, and I haven't found a reason not to do so. It may create obstacles to understanding ancient civilizations, but it may help us to understand better market economies.

I want to thank everyone who commented; at the Ph.D. level, it matters something, and I didn't think my comment would attract much attention.

--
Felipe Rodrigues Sousa
PhD candidate (University of Coimbra)