We can not validly study economy without appeal to a landmark and to an exchange reference measure, in the same way that in all science, the considered landmark and measure units should be define before a study.
As a reference and time units and length units are necessary to the establishment of physics laws, no advanced study can be conducted without the previous definitions of the economy reference frame and the associated measure unit.
An economic zone or a monetary zone is the base landmark of the economic study. What characterized it?
The space where the monetary agreement is manifest
Time, that is to say, average individuals life span which lives and dies.
Individual or collective (entreprenarial) production of goods and services
The goods and services exchange between individuals or individuals groups.
Individuals or individuals groups are inevitably brought to exchange, only for information, education, or more generally still link. Which therefore fundamentally characterize the economics zone it is all individuals which compose it. Economy exist everywhere and anytime as soon as individuals produced and exchange goods and services, and that regardless of goods and services nature. For instance, we can not define an economic zone empty of individuals. That is well individuals which constitute the only common and fundamental value of all valid economic landmark.
But to go further, this set of individuals evolve in time with births and dead, immigration and emigration. The economic zone could be imagined as a space time discreet on constant creation/destruction where each temporal point represents individual at limited life time.
It is a spacio-temporal welf on a continue, non static, discreet transaction, where each point of space-time is created at a determined date (birth of an individual) and at limited life duration which, on average, matches to life span which we will nominate “ls” in a considered economic zone.
That is the fundamental definition of Relativity in economics, all individual have personal and unique vision of value of all things and each individuals of individuals groups of economic zone is not able to impose to others a particular vision of what is value or not.
An economic zone is said to be pseudo-isolated when, for a given time duration, we can consider that it live independently or almost-independently opposite to exterior. Perhaps the case of economic systems on still autonomous islands, where the livelihoods of individuals is ensured by sufficient food production (which is also quite relative, see for example the case study of some ascetics), but also the case of a topologically complex group of individuals in a not connected space, transnational, even transcontinental. As long as this set shows an autonomy, we can consider it as a pseudo-single economic zone, able to self-manage their work flow and exchange, at least on a small period of time.
When there is goods or services exchanges, we talk about value exchange. X exchange with Y a value Vx = Vy = Px × Cx = Py × Cy, where “Px” represents the price in the common measure unity (called the common money) of population of X “Cx”.
This definition of value is perfectly relative to the observer which measure it, so if X consider that Vx = Vy, it is possible that Y consider Vy very bigger than Vx, and do not wear less. By aillor Z which observed this exchange may well judge according to his own reference that Vx and Vy does not have value.
Recall here how much men are fundamentaly not agreed all long of their history on respective value of their goods. Also equality of exchange values is not an independent economic criterion of the observer, which is also seen by the actions of donations ou taxation withou returns, and therefore non-symetrics, where equality of exchange values is not respected according the point of view.
This is for universals needs of value measure, that individuals agree on a common measure of exchange they call money. A define money give thus a common measure of value to all things in same unity, for a given observation landmark, which permits comparisons wealthier.
Money thus act not only of exchange tool between individuals of an economic zone, but also the only value independent from the observation landmark.
This being said, it exit historically and locally, a many different definitions of money, which involved fundamentally different types of exchanges, and which are often ignored by those which accepts to use it.
Those cases of ignorance of money nature used most of the time in a constraint way, are a violation of the contractual law of the economy basis, which suppose the acceptance of involved parts about the proposed exchange type.
We can without hesitation declare that the imposition of use of a non contractual money (not subject to a voluntary acceptance) is an act opposite to human right to dispose of his life for an economic part and a violation to constitutionals principles of liberty and equality.
And thus minimum in a real democracy, the official money can not really be acceptable only if it subject of a democratic elaboration in it definition, as in it validation, it acceptation it modification and it abandonment.