So, after reading the whole article I am pretty unconvinced by the Author - nor do I really understand his point beyond "Charlemagne hated the free market
Generally speaking, I think his point is to explain how the centralizing efforts of Charlemagne did not have the economic benefits he envisioned. This is Henry Hazlitt economics 101. Well-motivated economic policies of the state almost always carry with them unforeseen side effects that typically affect the economy in adverse ways. So while Carolingian policies didn't achieve hoped-for economic goals, they did allow the perpetuation of large scale military operations on a regular basis, which are not a possibility in a decentralized society with a largely unregulated economy (i.e. not significantly taxed and no central monetary authority). Hence, his supposition that attempts at building up of state authority and centralization are almost universally related to an ongoing desire to make war.
First off there doesn't seem to be any evidence presented that the Merovingians deliberately adopted a decentralized economy. Historically the Merovingian kings were known for seizing land and redistributing it to their followers and supporters.
I don't think that was his claim. He observed that prior to the Carolingian era, the Merovingian lands were largely de-centralized, and in the post-Carolingian era, they returned to decentralization because most people found the Carolingian reforms counter-productive.
Second, I do not buy his bit about the market wise Merovingians and their bi-metallic standard. Anyway, the reason that silver played an increasingly large role was simply because it was much more available. With the collapse of the Roman empire and the subsequent decline of trade between Th Eastern Europe and the rest of the world, the supply of Gold also decreased. Since the economy ran primarily on the barter system at the time (and most estates were self-sufficient to begin with and conducted little trade,) there would have been no need for government regulation of the economy. Of course, by the time of Charlemagne, trade had increased, and there was a need to ensure that the currency was not devalued by debasing (which had been fatal to the late Roman Empire.)
I think you're missing his point (or maybe you're making it for him). Silver was already coming into greater use due to market forces. Charlemagne was just building on this by creating an official legal tender. But the author claims that the market rejected Charlemagne's coinage, for whatever reason. The author doesn't claim to know what the reason was. There are several possibilities. Perhaps the purity of his coins was not up to the standards of what could be obtained in the open market among other sources of coinage. The author's theory is that the market feared the possibility of a state monopoly on currency (precisely because the state would then be free to devalue it as occurred in the late Roman period via decreasing gold/silver content). I think it's probably a combination of both.
In addition, the author says that the free market would have been perfectly capable of resolving issues in the currency supply in time (he appears to be of the school that the free market is "always" more efficient than the state.) This is evidently untrue though, because otherwise there would have been no need for the Carolingian monarchs to pass regulations.
Again, I think you're missing the point. The Carolingians didn't NEED to pass regulation. The Carolingian reforms were elective. Private coinage was working efficiently, because the market could select the purest coinage rather than be forced to use the coinage of a particular monarch. This naturally prevents the devaluation of currency via inflation. There was no currency crisis in the Merovingian era. Currency crises UNIVERSALLY occur due to monopolistic monetary policies of centralized authorities. Charlemagne wanted to coin currency and regulate it so he could more efficiently tax and rule over a geographically and culturally diverse empire. His monetary policy did nothing to serve the needs of the market. So it was his political and military goals that informed his monetary policy, not a desire to meet the economic needs of his people.
Furthermore, the author takes issue with Charlemagne's ban on usury and prohibitions on working on Sunday. I do not have much to say about this other than it was obviously his attempt to conform the Kingdom to Christian morality. The description of bans on usury as a "monetary crank theory" is quite ironic.
What do you make of the bishop of Verdun's position on usury, then? Also, I thought the author did a fine job addressing this when he explained that borrowing money in the early middle ages typically wouldn't have been for capital investments but for life or death necessities, thus accounting for why charging interest to a borrower would be seen as immoral. In the case of capital loans, it would certainly be moral. So a distinction must be made.
It seems to me that the quote regarding individual rights is meant to be taken as relevant to both the decentralized Merovingian state and the centralized Carolingian one. The point seems to be that regardless of the who was in charge and what their economic/military policies were, individual rights remained the same because they were seen as the domain of God and his Church. so even the greatest statist of the time would not have infringed upon them.
I don't think that is the point of the statement. The author points to various sources that one could depend on for securing one's rights in the Merovingian era (one's family, one's community, one's local lord of chieftain, the Church, etc.). But as efforts to centralize political authority naturally lead to the dimunition of influence for lower level social entities, the need arises to codify individual rights in constitutional form to protect individuals in the larger state, because the individual has less influence in such a large realm and is easily overlooked (whereas he might have previously gone to his local lord or ecclesial authority to seek advocacy, for example). Thus, declarations of rights (which became so fashionable in the Enlightenment era) were not necessary in the Merovingian era in order to achieve the same level of rights, due to the natural localization of influences capable of protecting an individual's rights.