Money 1 – A Creation Myth

In this piece, I take “Macroeconomics” by Greg Mankiw, the bestselling undergraduate textbook, as the source for this story.

A history of money

In the beginning, there was barter
and a rudimentary economy was based on it. This is extremely inefficient as you have to walk around all day carrying lots of goods, hoping you bump into someone who has something you need who at the same time wants something of yours and will trade you for it.

Efficiency demanded the use of commodities….
Given how poorly organised this world would have been, “it is not surprising that in any society, no matter how primitive, some form of commodity money arises to facilitate exchange”. “Most societies in the past have used a commodity with some intrinsic value for money”. We can see this because archaeologists have found lots of gold, silver and copper coins from previous civilisations.

A really nice example of recent commodity money is the use of cigarettes for currency in a POW camp in WW2. This is an excellent example of why commodity currencies existed and how they operate.

As society evolved thus did “fiat money”….
A modern development in the history of money is the development of “fiat money” which is “money that has no intrinsic value”. This occurs via a process of “evolution from commodity to fiat money”. The process by which this happens is rather mysterious but “in the end the use of money in exchange is a social convention: everyone values fiat money because they expect everyone else to value it.”

Modern money

Money is the stock of assets that can be readily used to make transactions” and it can be defined by its uses which are:

  1. Store of value
  2. Unit of account
  3. Medium of exchange

Between history and mythology

Unfortunately, as so often is the case with creation myths, none of this is actually true. Understanding what money is and why economists are taught its history in such a strange way is important. In fact, I would say it is central to understanding current economic policy and also how best to invest.

Myth #1 In the beginning there was barter

There is no evidence of any society has ever used barter as their primary means of exchange. This should be unsurprising as it would be horrifically inefficient.

Myth #2 Commodity money was the primary form of money for most of history

This myth is more serious and way more pervasive.
However the evidence from the existence of coins far from backs it up, I think it is good evidence of the opposite.

Imagine we are in ancient Rome and we have a Denarius coin in front of us
(Deni from Latin “containing ten” originally was the value of 10 asses)

It has a nice picture of Hadrian on it, “he” of the wall.
It was made of silver and so has an intrinsic value from its weight in silver
(there are examples of use of gold in coins too – the history is interchangeable)

Consider this, let:

A= intrinsic melt-down value of the coin

B= face value on the coin

Then scenarios are:

A > B the coin would not exist, it would be melted down.

A = B why mint it in first place? Why bother calling it a Denarius at all and put the Emperor’s face on it? It would be simpler just to weigh it. There is no benefit for the government to go to the trouble and expense of minting these things.

B > A Now there is a reason to mint it – a profit! The difference (B–A) is known as “seignorage”. We know this was a main source of income for monarchs for centuries from records. But if B>A then there is no strong link between the intrinsic value of the metal and the value of the money. It sets a lower limit but nothing more.
So what is the difference to fiat money? Not much. History indeed has little evidence for a prevalence of commodity money.

But what about the example of cigarettes in the POW camp?
I love this example because it is correct, and utterly misleading. There is an important reason why a commodity currency was used. It is because there was no way to enforce an obligation as the members of the economy were not in control of their society (see below for why this matters).

Myth #3 Money is an asset

Money is not a thing, or an asset like any other asset in the economy. It is much more special than that. It is a ledger item which always consists of an asset and a liability which come into existence at the same time. There is nothing else like it and it is central to the functioning of the economy. I will delve into this in the following posts.

A common error when struggling with such an abstract concept, it is often much easier and more natural to think in tangible terms. An analogy for this is units of measurement. It is now “obvious” that the concept of measurement is conceptually separate from any physical object. I can separate the concept of “1 metre” from the physical reality of a “piece of metal 1 metre long”. Although it is hard to imagine than this was not always obvious for humans, it was certainly not the case in ancient societies. In fact, it is striking how well these societies were able to operate, before the concept of number being separable from their physical objects, allowed formal arithmetic.

Myth #4 Money can be defined by its uses

This myth is again common but is a non-unique definition for money. There are many, many assets which could be used for the functions:

  1. Store of value
  2. Unit of account
  3. Medium of exchange

For example: dollars, gold, bitcoin, cigarettes, diamonds, canned food, oil etc.
In fact, anything non-perishable as bananas would not store well. The concept that in a mainstream economics they assume that anything can be used for money is important. Economic theories have developed from it, often containing the hidden assumption that money is not special and can largely be ignored. It is an asset like any other asset, is priced in the same way as any other asset. Therefore we should not be surprised that all the output from these models show no important role for money in the economy. I would have hoped the financial crisis would have exposed this as a myth.

Myth 5 Fiat money is a modern development

In fact, it is the oldest form of money.
I would prefer to say that “fiat money” means “money” and that “commodity money” is best defined simply as a “commodity”.


The story of money taught to economics students contains many a myth.
Next, I will tell an alternative story of money. The ideas I will present are not difficult.

But as Keynes said, “The difficulty lies not so much in developing new ideas as in escaping from old ones.”

Is Climate Science True?

If this blog were the BBC, in an effort for impartiality, I would give equal time to 2 ideas:

  1. Climate change is completely true
    Agreed by all reputable scientists and means drastic action needs to be taken immediately
  2. Climate change is a hoax
    Devised by the Chinese to limit the US economy and we need do nothing

However, I’m not bound by any such desire for manufactured impartiality so would like to ignore climate denial theories. I want effective action to be taken and I’m interested in why the first argument is failing to find broad enough support against those who want to dismantle the Paris Agreement.

The Science

I think I can reasonably simplify the scientific arguments to this:

  1. There is an empirical relationship between carbon and temperature
  2. There is a causal theory relating the two, the greenhouse effect
  3. There is no better theory, in fact no other credible theory

The criticisms for each item can be summarised like this:

  1. Poor and incomplete data
  2. The underlying system is dynamic and complex
  3. The models are not very precise with large amounts of uncertainty.

The responses I have seen to these criticism from climate change scientists are:

  1. We are collecting more data all the time. We are cleaning up the old data sets.
  2. We are building more complex models which incorporate more variables
  3. We are working to improve our accuracy with better models to reduce the level of uncertainty.

Coming from a macroeconomics background, the criticisms wouldn’t bother me much. We face them all the time. The responses from the climate change scientists do bother me however. If this reflects their research programmes, I fear they are heading in the wrong direction, sharing many of the methodological problems we see in macro and likely making the same mistakes.

My view

My preferred responses to the criticism would be

  1. Yes, the data is poor and incomplete. Not much we can do about that. We will not clean up data to pretend it is better than it is.
  2. Yes, it is dynamic and complex. Attempting to making models more complex would mean data-mining the limited data sets to produce models which are pretty but have no validity. Simple models of complex systems often work much better. Read the Borges short story ( for an elegant refutation of the idea that seeking perfection in models leads to good outcomes.
  3. Accurate forecasts are not possible because we do not have ‘out of sample’ data and associated feedback. There is little new data to use so we cannot properly test hypotheses in the way we can with weather forecasting.

The good news is that we do not need accurate forecasts because:

  1. If our model provides an unbiased best estimate and uncertainty is two-sided, then the level of uncertainly around it does not affect the policy response. Essentially the policy response will be versus the expected increase in temperature.
  1. We are providing conditional, not unconditional forecasts.
    To take an analogy, I am thinking of running the London marathon next year. Please estimate how long it will take me to run it i) in running kit ii) wearing a gorilla costume. I would strongly expect that your confidence in both of your answers is very low. However, I bet you are very confident that ii) will take longer than i).

Financial markets can be a very good training ground for learning about practical model building and their methodical dangers. Most of us have been seduced by beautiful models with great back tests with desirable correlations and high Sharpe ratios. But then trying to use them to make money, we find they had no predictive qualities at all. After enough painful experiences, we learn to be highly suspicious of any model that fits the data too well – it is the obvious symptom of data-mining. The models that work in practice are the ones that are intuitive, simple and accept that the world is a messy complicated place.

What climate change scientists and macro-economists can actually do have a lot of similarities. We do not know what the temperature will be on October 23rd 2087 but we have a good guess it will be higher if there is more carbon in the atmosphere.


Since I discussed models in my last post, I could not resist saying something quickly about what they are for. This is a very important topic and one I will frequently return to.

But for now, I will just give you a brilliant short story from the most inventive and thought-provoking author I know.

Jorge Luis Borges. “On Exactitude in Science” or “Del rigor en la ciencia”.

Can you put a price on the environment?

I am an economist by training, experience and by inclination so the answer seems an obvious yes. Welfare economics generally looks at exactly these sorts of questions. However, the debate and current policy mix for Climate Change does not appear how I would expect it to, especially given the lack of agreement on carbon pricing which has dropped out of the discussion.

Assigning monetary value?

A common mistake that economists make is, because a given model works for some aspects of human behaviour, they assume it can always be used and possibly generalised to all human behaviours, often by adding some sort of arbitrary assumption to make it fit. The consensus in neoclassical modelling is for a marginalist approach with rational agents.

Take gift giving, it is economically inefficient but still takes place. The neoclassical approach is to assume that cash giving has an unexplained stigma or that buying your lover a thoughtful gift acts as signal that you love them. Of course, these fail to resonate with our actual experience of gift giving and receiving, and so fail the common-sense approach.

This is a classic logic error – there are many (infinite?) ways to model and explain behaviour. Just because you have one that you like does not mean it is the only one or that it must be superior to the others. If to make your model fit the external reality you are required to add counterintuitive assumptions then this can often sign to rethink your entire approach.

What other approaches are there?

The environment is a moral not an economic question

This idea was sparked reading Michael Sandel’s “What Money Can’t Buy”.
As a political philosopher, he is highly critical of the current trend towards adding commercial thinking and monetary values into our lives, using moral arguments of unfairness and degradation of values. There are many examples: paying to avoid queuing, the rise of corporate boxes at venues, paying to get a nicer prison cell and, in this category, he also places the environment.

Another famous example of a counterproductive effect of replacing a moral code with a monetary incentive is a school adding a fee for late pick-up of children after school. Parents were much happier paying a price for lateness than infringe a moral obligation to pick up the children on time and the incidence increased. Related to this, when people are paid for blood donations, the amounts and quality of blood donated both fall.

When Sandel in 1997 wrote a piece in the New York Times arguing against carbon trading, he was inundated with “scathing letters – mostly from economists” who assumed that he simply did not understand that their model, that trading would always be good, was obviously true. 20 years later some economists may be more sympathetic to the idea that not everything should be analysed in this way.

A different view?

Do the efforts to “stigmatize” excessive carbon usage and “promoting virtuous attitudes” work? Moral codes in society are very powerful. But as a prevention mechanism, they do not always work. They may not be as universally shared as their advocates like to assume; If you want to reduce teen pregnancy the approach of teaching that sex before marriage is immoral and the promotion of abstinence have been shown to be highly ineffective. The attempt to change people’s behaviour on carbon consumption by stigmatizing it appears to me to have the same flaw. People may feel a little guilty but will not actually change their behaviour, whilst the moralisers can enjoy the feeling of superiority, getting us nowhere.

I was once memorably informed that my willingness to experiment with models and analysis that put a monetary value on human life was “sociopathic”. I did wonder at the time if they knew or cared how counterproductive it is to alienate sympathetic non-believers if your objective is to influence behaviour.

Lexicographic vs marginal preferences

Amartya Sen is a wonderful writer on justice, development and social choice who developed ideas in welfare economics beyond thinking purely about Pareto optimality. I was recently reminded of this concept in Marc Lavoie’s “Introduction to Post-Keynesian Economics”. It was striking to me that I had forgotten about it which implies it is not commonly used.

Faced with needs, the idea is that people do not make marginal decisions across every item but rather make choices only within categories. There is a hierarchy of needs, and only when the essential ones are obtained, then the next category can be bought. Therefore, substitution of goods only happens within categories and not between them.

For the environment, people that think that climate change is a compelling moral issue then discussing the price is bizarre and inappropriate. It is a moral need and comes in a very important category. For people who have consumption desires they find more pressing such as housing, clothing and food, then the morality of climate change is in a lower category and so not highly valued. This helps explain the observation that when asked how much they value the environment people’s answers tend to be extremely high numbers or extremely low ones. There is no smooth substitution along an indifference curve. It also explains why people express that they care enormously about the environment when the economy is doing well and it is not mentioned during a recession.

This sort of heterodox critique of neoclassical marginalism is compelling, but the next step of suggesting a policy is lacking. Lavoie says that “post-Keynesians have never really developed their views on consumer choice in any systematic way” and only have “insights”.

Where next?

I am left thinking that at pure moral non-market approach to dealing with Climate Change is not effective. A lexicographic approach gives a useful description that fits observed behaviour but does not give me any useful approaches to designing policy. So, I return to welfare economics and thinking in terms of cost-benefit analysis and externalities.