Tag Archives: money

Bitcoin and the Blockchain

It’s hard to believe that a whole year has passed since I last wrote on the topic of bitcoin, and my remaining 1 bitcoin is worth rather less than it was back then. During the week I presented at the Sydney Financial Mathematics Workshop on the topic of bitcoin, taking a rather more technical look at the mechanics of the blockchain than in my previous posts here on the Mule. For those who are interested in how Satoshi Nakamoto solved the “double spend” problem, here are the slides from that presentation.

Bitcoin and the Blockchain

As part of my preparation for the presentation, I read Bitcon: The Naked Truth About Bitcoin. If you are a bitcoin sceptic, you should enjoy the book. If you are a Bitcoin true believer, you will probably hate it. It is over-blown in parts and gets a few technical details wrong, but I am increasingly convinced by the core argument of the book: the blockchain is an extraordinary innovation which may well change the way money moves around the world, but bitcoin the currency will prove to be a fad.

Bitcoin: what is it good for?

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Bitcoin has been a hot topic in the news over the last few weeks.

The digital currency has its adherents. The Winklevoss twins, made famous by the movie Social Network after suing Mark Zuckerberg for allegedly stealing the concept of Facebook, now purportedly own millions of dollars worth of Bitcoins.

It also has its detractors. Paul Krugman has argued that the whole enterprise is misguided. Bitcoin aficionados are, he writes, “misled by the desire to divorce the value of money from the society it serves”.

Still others cannot seem to make up their mind. Digital advocacy group, Electronic Frontier Foundation (EFF) accepted Bitcoin donations for a time, but became uncomfortable with its ambiguous legal status and shady associations, such as with the online black market Silk Road, and decided to stop accepting Bitcoin in 2011. A couple of years on and the EFF’s activism director is speaking at a conference on Bitcoin 2013: The Future of Payments.

Recent media interest has been fuelled by the extraordinary roller-coaster ride that is the Bitcoin price. In early April, online trading saw Bitcoins changing hands for over US$200. At the time of writing, prices are back below US$100. As with many markets, it’s hard to say exactly what is driving the price. Speculators, like the Winklevoss twins, buying Bitcoins will have helped push up prices, while reports that Silk Road has suffered both a deflation-driven collapse in activity and hacking attacks may have contributed to the down-swings.

Although not obvious on the chart above, dramatic price movements are nothing new for Bitcoin. Switching to a logarithmic scale makes the picture clearer. After all, a $2 fall from a price of $10 is just as significant as a $40 fall from a price of $200. The 60% fall from $230 to $91 over April has certainly been dramatic. But back in June 2011, after reaching peak of almost $30, the price fell by 90% within a few months.

The volatility of Bitcoin prices is orders of magnitude higher than traditional currencies. Since the start of the year the price of gold has been tumbling, with a consequent spike in its price volatility. Even so, Bitcoin’s volatility is almost ten times higher. The chart below compares the volatilities of Bitcoin, gold and the Australian dollar (AUD).

A week or so ago, armed with this data, I was well advanced in my plans for a blog post taking Bitcoin as the basis for a reflection on the nature of money. I would start with some of the traditional, text-book characteristics of money. A medium of exchange? Bitcoin ticks this box, with a growing range of online businesses accepting payment in Bitcoin (including WordPress, so not just underground drug sites). A store of value? That’s more dubious, given the extremely high volatility. It may appeal to speculators, but with daily volatility of around 15%, it’s hard to argue that it is a low risk place to park your cash. A unit of account? Again, the volatility gets in the way.

That was the plan, until a conversation with a colleague propelled me in a different direction.

She asked me what this whole Bitcoin business was all about. Breezily, I claimed to know all about it, having first written about Bitcoin two years ago and then again a year later. I launched into a description of the cryptographic basis for the operation of Bitcoin and went on to talk about its extreme volatility.

I then remarked that when I first wrote about it, it was only worth about $1, but had since risen to over $200.

“So,” she asked, “did you buy any back then?”

That shut me up for a moment.

Of course I hadn’t bought any. What gave me pause was not that I had missed an investment opportunity that would have returned 20,000%, but that I was so caught up in the theory of Bitcoin that it had not occurred to me to see what transacting in Bitcoin was actually like in practice. So I resolved to buy some.

This turned out not to be so easy. While there are many Bitcoin exchanges, paying for Bitcoins means jumping through a few hoops. Perhaps because the whole philosophy of Bitcoin is to bypass the traditional banking system. Perhaps because banks don’t like the look of most of them and will not provide them with credit card services. Whatever the reason, your typical Bitcoin exchange will not accept credit card payments. Many insist on copies of a passport or driver’s licence before allowing wire transactions, neither of which I would be prepared to provide.

Eventually I found BitInnovate, which allows the purchase of Bitcoin through Australian bank branches. Even so, the process was an elaborate one. After placing an order on the site, payment must be made in person (no online transfers), in cash, at a branch within four hours of placing the order. If payment is not made, the order is cancelled. Elaborate, but manageable, and no identification is required.

But before I could proceed, I had to set myself up with a Bitcoin wallet. As a novice, I chose the standard Bitcoin-Qt application. I downloaded and installed the software, and then it began to “synchronise transactions”. This gets to the heart of how bitcoins work. As a purely digital currency, they are based on “public key cryptography”, which is also the basis for all electronic commerce across the internet. The way I make a Bitcoin payment to, say, Bob is to electronically sign it over to him using my secret “private key”. Anyone with access to my “public key” can then verify that the Bitcoin now belongs to Bob not me. Likewise, the way I get a Bitcoin in the first place is to have it signed over to me from someone else. In case you are wondering what one of these Bitcoin public keys looks like, mine is 1Q31t2vdeC8XFdbTc2J26EsrPrsL1DKfzr. Feel free to make Bitcoin donations to the Mule using that code!

In this way, rather than relying on a trusted third party (such as a bank), to keep track of transactions, the ownership of every one of the approximately 11 million Bitcoins is established by the historical trail of transactions going back to when each one was first “mined”. Actually, it’s worse than that, because Bitcoin transactions can involve fractions of a Bitcoin as well.

So, when my Bitcoin wallet told me it needed to “synchronise transactions”, what it meant was that it was about to download a history of every single Bitcoin transaction ever. No problem, I thought. Two days and 9 gigabytes (!) later, I was ready for action. Now I could have avoided this huge download by using an online Bitcoin wallet instead, but then I would have been back to trusting a third party, which rather defeats the purpose.

The cryptographic transaction trail may be the brilliant insight that makes Bitcoin work and I knew all about in it theory. But in practice, it may well also be Bitcoin’s fatal flaw. Today, a new wallet will download around 10 gigabytes of data to get started, and that figure will only grow over time. The more successful Bitcoin is, the higher the barrier to entry for new users will become. I suspect that means Bitcoin will either fail completely or simply remain a niche novelty.

Still, it is an interesting novelty, and despite the challenges, I decided to continue with my investigations and managed to buy a couple of Bitcoins. The seller’s commission was $20 and falling prices have since cost me another $20 or so. So, I am down on the deal, but, as I have been telling myself, I bought these Bitcoins on scientific rather than investment grounds.

Of course, if the price goes for another run, I reserve the right to change my explanation.

Where is the money coming from?

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It has been quite some time since I wrote about the mechanics of money, but today I am at it again. The catalyst is not, as some might expect, the recent discussions about the possibility of the US Treasury minting a trillion dollar coin, but rather a recent discussion I had with a banker about deposits on a small tropical island.

While deposit levels at banks in Australia are below upcoming regulatory minimums, leading to intense competition in the pricing of term deposits, the banker I spoke to was facing the opposite problem in the small nation of Paradise Island (not its real name).

As he told the story, despite offering rather unattractive interest rates on deposits, deposit balances had continued to grow. Worse, demand for loans was weak and so the bank was forced to keep growing balances on deposit with the island nation’s central bank. Since banks like to diversify their investments, this situation was not ideal. Ordinarily, he said, deposits would build up as exporters took in payments for their goods, but periodically these balances would be swept out again as they remitted their profits to offshore parent companies. This did not seem to be happening any more. Exactly why these deposits were growing was a mystery and, short of closing the doors of all their branches, he did not really know how to stop these balances from growing.

With years of reading Bill Mitchell under my belt, I knew that the way to think about this question was to take a macro perspective rather than thinking from the perspective of one bank.

The first thing I focused on was the balances with the central bank. A popular misconception is that banks can choose between holding deposits with the central bank or lending the money to their customers. In fact they cannot. The central bank itself only has two types of “customer”: banks and the government. You and I cannot walk into the central bank and open up an account. This means that the only thing that can happen with central bank balances is that they move around from one bank to another or to and fro between the government and banks.

Imagine for a moment that the bank arranges a $100,000 loan for me to buy a nice little shack on one of Paradise Island’s beaches. If the shack vendor banks with my bank, then our bank will see both its loans and its deposits increase by $100,000. On the other hand, if the vendor banks elsewhere, my bank will have to transfer $100,000 to the vendor’s bank. This is done by moving money between the banks’ respective accounts with the central bank. So, in this case, my bank has an increase in its loans of $100,000 and a decrease of $100,000 in its deposits with the central bank. But that central bank deposit has not left the system (and it has not gone to me). Rather, it has moved from one bank to another.

While there will be movements in central bank balances in this fashion from one bank to another in the normal course of business transactions, balances will tend to average out to reflect each bank’s market share. So, my banker friend is unlikely to be alone in seeing deposits with the central bank growing. Indeed, looking at the aggregate bank balances with the Paradise Island central bank, it becomes evident that there is a systematic trend.

Aggregate Balances with the Central Bank

So how does this happen? The most likely explanation is that the balances are coming from the government. As the government spends money, behind the scenes there will be money moving from the government’s account at the central bank to the accounts of commercial banks. This can happen if the government is running a deficit, spending more money than it is receiving. But that is not the case here. In fact, Paradise Island has been running a surplus of late.

A bit more digging through the national accounts reveals the answer. Paradise Island receives aid from larger developed nations and the government has been spending most, but not all of this aid. The twist is that this aid has come in the form of foreign currency, which the government then deposits with the central bank in return for local currency balances which it is then able to spend. As a result, the central bank’s foreign asset balances have also been steadily growing. The similarity of these two charts is no coincidence: the two sides of a balance sheets must balance and the growth in the central bank’s assets directly mirrors the growth in their liabilities, in the form of commercial bank deposits. This is an example of what is known as “grossing up the balance sheet”.

Foreign Assets of the Central Bank

So the growth in bank deposit balances with the central bank has nothing to do with Paradise Islanders hoarding money or choosing not to remit their profits offshore. Instead it is the direct result of the government spending its aid money. If the local banks want to have less of their money tied up in deposits with the central bank, rather than pointlessly trying to incentivise their customers to borrow or place their deposits elsewhere, they should consider encouraging the central bank to sell some of their foreign assets, reversing the grossing up of the balance sheet.

For me the most interesting aspect of this discussion is the fact that even if you can see exactly what is going on inside your own institution, it can be difficult to understand the workings of the system as a whole.

Bitcoin revisited

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Just over a year ago, I wrote about the digital “crypto-currency” Bitcoin. It has been an eventful year for Bitcoin.

Designed to provide a secure yet anonymous, decentralised means for making payments online, the first Bitcoins were virtually minted in 2009. By early 2011, Bitcoin had begun to attract attention. Various sites, including the not-for-profit champion of rights online, the Electronic Frontier Foundation (EFF), began accepting Bitcoins as payment. But when Gawker reported that Bitcoins could be used to buy drugs on “underground” website Silk Road, interest in the currency exploded and within a few days, the price of Bitcoins soared to almost $30.

This kind of attention was unwelcome for some, and shortly afterwards EFF announced that they would no longer be accepting Bitcoins, fearing that this would be construed as an endorsement of the now controversial currency. Around the same time, the first major theft of Bitcoins was reported and the Bitcoin exchange rate fell sharply.

Bitcoin Exchange Rate

More recently, another high-profile theft has caused ructions in the Bitcoin economy, prompting e-payments provider and PayPal competitor, Paxum, to abandon the Bitcoin experiment, which in turn forced one of the larger Bitcoin “exchanges” to shut down. The anonymity of Bitcoin is a design feature, but it also makes it almost impossible to trace thieves once they have their virtual hands on Bitcoins.

How much damage this does to the fledgling currency remains to be seen, but it certainly makes for a volatile currency. The free-floating Australian dollar is a reasonably volatile real-world currency but, as is evident in the chart below, Bitcoin volatility is an order of magnitude higher. That in itself is reason enough for any online business to think twice about accepting Bitcoins.

Rolling 30 day volatility (annualised)

Whatever its future, Bitcoin is a fascinating experiment and, even if it does not survive, digital currencies of one form or another are surely here to stay.

Data sources: Bitcoin charts, Bloomberg.

Bristol Pound

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Recently, a colleague drew my attention to the “Bristol Pound“, an example of a “local currency“. Ah yes, I said, that’s been around for a few years now. Embarrassingly, I later realised I was thinking about the “Brixton Pound“. Having attended many concerts at the legendary Brixton Academy (Nick Cave, Ministry and the Sugarcubes among them), I really should have known the difference between Bristol and Brixton!

There are now a number of local currencies in Britain. The first to appear in recent years was the “Totnes Pound“, launched in March 2007. According to their website, the benefits of the Totnes Pound are:

To build resilience in the local economy by keeping money circulating in the community and building new relationships
To get people thinking and talking about how they spend their money
To encourage more local trade and thus reduce food and trade miles
To encourage tourists to use local businesses

The aims of the Brixton Pound, the Bristol Pound and the other local currencies are essentially the same. As far as I can tell, the take up of these currencies to date has been modest, but the Bristol Pound represents an interesting new development. Not only does it have a far slicker website, but it also offers payment by mobile phone. Perhaps most significantly, according to the FAQ, “Business members that pay business rates to Bristol City Council will be able to pay in Bristol Pounds.”

A key tenet of “Modern Monetary Theory” is that the value of fiat money is not underpinned by gold or any other commodity; rather its value derives from the government levying tax in that currency. Since almost everyone has to pay tax at some point, this creates a base level of demand for the currency. So, perhaps the fact that the Bristol City Council is supporting the Bristol Pound will enhance its take-up prospects. It would be even more interesting if the council decided that they would only accept Bristol Pounds as payment for rates.

Return of the Drachma?

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It has been reported that Greece is considering leaving the euro and re-establishing its own currency*.

More than a year ago, I argued that being part of the euro seriously exacerbated Greece’s economic woes, and for the reasons given there, I do think that re-establishing sovereignty over its currency is in Greece’s interests in the long run. Nevertheless, it would be a painful process exiting the monetary union.

To begin with, there are all sorts of practical complexities. The switch to the euro was an enormous project, years in the planning and to switch back would require major logistical and systems changes for banks and businesses across the country. Mind you, the work involved may act as a stimulus to employment! The other challenge, is that Greece still has significant quantities of public and private debt denominated in euro. Inevitably, there would be defaults and restructuring of this debt. That, combined with the fact that the new currency would be launched by a country known around the world to be in dire economic straits, would result in ongoing weakness of the new currency. While a weak currency would have some advantages, making Greece’s exports far more competitive than they have any hope of being while the country retains the euro, imports would become very expensive and there would be significant inflationary pressure. The problems Iceland has faced since its default provide a useful comparison, although Greece does have the advantage of a broader domestic production base.

So, while an exit from the euro would be an unpleasant experience, it is probably just the medicine that patient requires.

* Thanks to @magpie for drawing this article to my attention.

S&P being silly again

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The debt rating agency Standard and Poor’s (S&P) has placed their rating of the US on negative outlook. What this means is that they are giving advance warning that they may downgrade their rating of the US from its current AAA level (the highest possible rating). Their actions were motivated by concern about “very large budget deficits and rising government indebtedness”.

To me this shows that S&P do not have a good enough understanding of macroeconomics to be in the business of providing sovereign ratings. How can I doubt such an experienced and reputable organisation as S&P? Well, keep in mind that this is the same agency which maintained investment grade ratings for the likes of Bear Stearns, Lehman Brothers and AIG right up to the point where these firms were on the brink of collapse (while it was only Lehman that actually failed, that was only because the other two were bailed out). Likewise, it is the same agency which assigned investment grade ratings to sub-prime CDOs and other structured securities many of which only ended up returning cents in the dollar to investors during the global financial crisis.

Of course many commentators are very nervous about the growth in US government debt (notably, the bond market seems far more sanguine) and typically assert, with little justification, that growing government debt will lead inevitably to one or more of:

a failure of the government to be able to meet its debt obligations,
rising inflation as the government seeks to deflate away its debt (and interest rates will rise in anticipation of this future inflation), and
a collapse of the currency as the government seeks to devalue its way out of the problem.

Before considering how likely these consequences really are, it is important to emphasise that while there is a widespread tendency to label all of these as a form of “default” by the government it is only the first of the three, a failure of the government to make its payment obligations, that the S&P rating reflects.

In fact, I do not consider any of the three consequences above to be inevitable. The quick and easy counter is to point to Japan. As its government debt swelled to 100% of gross domestic product (GDP) and beyond, it never missed a payment, would have loved to generate a bit of inflation but consistently failed year after year and, while its currency has its ups and downs, the Yen remains one of the world’s solid currencies. While I certainly do not think that the US should aspire to repeat Japan’s experience over the last couple of decades (I would hope for a better recovery for them), this point should at least dent the simplistic assumption that default, inflation or currency collapse follow rising government debt as night follows day.

Since it is only a true default that is relevant for the S&P rating, it is worth considering more specifically how likely it is that the US government will be unable to honour its debt obligations. Regular readers of the blog will know that I regularly make the point at the heart of the “modern monetary theory” school of macroeconomics, namely that in a country where the government is the monopoly issuer of a free-floating currency, the government cannot run out of money. If your reaction to that is “of course they can print money, but that would be inflationary!”, ask yourself why that did not happen in Japan and then remind yourself that even if it did happen, it is not relevant to the S&P rating.

There is one important caveat to this monopoly issuer of the currency argument. While it certainly establishes that the US government will never be forced to default on its debt, it is still possible that it could choose to default. This choice could come about in a dysfunctional kind of way since the US imposes various constraints on itself, in particularly a congress legislated ceiling on the level of debt the government may issue. So it is possible that a failure of congress to agree to loosen these self-imposed constraints could end up engineering a default. Now that is a more subtle scenario than the one that S&P is worried about, but since it is possible, it is worth considering how serious debt-servicing is becoming for the US government. To make a comparison over time meaningful, I will take the usual approach of looking at the numbers as a proportion of GDP. Taking the lead from a recent Business Insider piece*, the chart below shows US government interest payments as a share of GDP rather than the outright size of the debt. This has the advantage of taking interest rates into account as well: even if your debt is large, it is easier to meet your payment obligations if interest rates are low than if they are high.

US federal government interest payments as a share of GDP

So the interest servicing position of the US government has actually improved of late and is certainly much better than it was in the 1980s and 1990s. So why is S&P reacting now? I would say it is because timing is not their strong suit (and they do not really understand what they are doing). Ahh, you say, but what happens when interest rates start going up? Since the US Federal Reserve controls short-term interest rates and of late, through its Quantitative Easing programs, has been playing around with longer-term interest rates as well, the US government is in a somewhat better position than a typical home-borrower, and interest rates will only start to rise once economic activity picks up again. Then the magic of automatic stabilisers come into play: tax receipts will rise as companies make more profit and more people are back at work, and unemployment benefits and other government expenditure will drop and the growth of government debt will slow or reverse.

So, there is no need for panic. Once again, the rating agencies are showing that we should not be paying too much attention to them. After all, as they all repeatedly said in hearings in the wake of the financial crisis, their ratings are just “opinions” and not always very useful ones at that.

Data Source: Federal Reserve of St Louis (“FRED” database).

* As Bill Mitchell, @ramanan and others have noted the Business Insider chart, while looking much the same as my chart, has the scale of the vertical axis out by a factor 10.

Virtual currency

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Thanks to my new job, the rate of Stubborn Mule posts has declined somewhat over the last few weeks (to say nothing of Mule Bites podcasts!). Still, my commute has allowed me to catch up on my podcast listening and a particularly interesting one was the recent Security Now episode about the “virtual currency” Bitcoin. Here is how Bitcoin is described on their website:

Bitcoin is a peer-to-peer digital currency. Peer-to-peer (P2P) means that there is no central authority to issue new money or keep track of transactions. Instead, these tasks are managed collectively by the nodes of the network.

Given that e-commerce is already widespread on the internet, what exactly is new about this idea of a virtual currency? The key to this question is understanding the difference between money in the form of “currency” (notes and coins) and money in the form of balances in your bank account. Currency is essentially anonymous. If I hand you a $10 note, we don’t need anyone to facilitate the transaction and you can take that $10 and spend it with no further reference to me or anyone other else. To move $10 from my bank account to yours is quite different. Before we could even start, we both had to provide extensive identification to our respective banks to open bank accounts. Then, you would have to provide me with enough account information for me to instruct my bank to transfer money from my account to yours. Both banks would retain records of the transfer for a long period of time and, if the transaction was rather bigger than $10, the chances are that there may even be requirements for our banks to notify a government agency in case we were engaged in money laundering. Even if I paid you using a credit card, the information exchange would be much the same.

The Bitcoin virtual currency aims to mimic some of the essential characteristics of currency while allowing transactions to be conducted online. To do so, it makes very creative use of a powerful encryption technology known as “public key cryptography”.

Public key encryption involves encrypting data in a rather unusual way: one key is used to encode the data and a different key is used to decode the data. This is in contrast to “symmetric key encryption” in which the same key is used for both encoding and decoding data. To appreciate the difference, consider a less electronic scenario. I want to exchange messages with you using a locked box and ensure no-one else can open it. If we already have identical keys to the one padlock there is no problem. I simply pop my message in the box, pop on the padlock and post it to you. When you receive the box, you can use your key to open the box, read the message, reply and pop the same padlock on the box before sending it back. But what do we do if we don’t both have keys to the one padlock? There is a tricky solution. I put the message in the box, secure it with my padlock and send it to you. Once you get it, although you cannot open my lock, you add your own padlock to the box and return it to me. Once I get it back, I unlock my own lock and send the box back. You can then open your lock and read my message. While in transit, no-one can open the box. It’s certainly an elaborate protocol and, of course, I’m ignoring crowbars and the like, but it gives a rough analogy* for how public key encryption works.

When it comes to data encryption, both users will create a “key pair”. One key they keep to themselves (this is known as the “private key”) and one key they can share with the world (the “public key”). I can then let you (and indeed the whole world) know what my public key is. When I want to send you a message, I encrypt it using your public key and send it to you. The only way to decode it is using your private key, which only you have. Even though everyone can find out what your public key is, only you can decode the message. When you want to send a message back to me, you encode it using my public key. So, anyone who knows my public key can send me a message for my eyes only. As a side benefit, public key encryption can also provide authentication. If you send me a message encrypted using my public key, I would ideally like to confirm that it really came from you not someone else (after all, everyone knows my public key). To deal with this, you can also send a copy of the same message encoded using your private key. Once I have decoded your message with my private key, I can also decode the second message using your public key. If the two messages are the same, I know that whoever sent me the encoded message also had access to your private key, so I can be reasonably sure it was you. In practice, authentication works a little bit differently to this, using a “hash” of the original message (otherwise anyone could decode the secret message using your public key). This authentication process is known as “digital signing”.

All of that may seem like a bit of a diversion, but public key cryptography is at the heart of the Bitcoin idea. Essentially, a Bitcoin is a blob of data and if I want to give you one of my Bitcoins, I add your public key to the blob and then sign it using my private key. This means that anyone who has access to my public key (i.e. the whole world) can confirm that I intended to pass the coin onto you. As a result, Bitcoins have their entire transaction history embedded in them! To decide who “owns” a Bitcoin, we just need to look at the last public key in the transaction chain. Whoever owns that key, owns the Bitcoin.

“How is that anonymous?” I hear you ask. Since “keys” are just strings of data themselves, there is no reason you have to advertise the fact that, say “6ab54765f65” is your public key. While the whole world can see that the owner of “6ab54765f65” owns a number of Bitcoins, that does not mean that anyone has to know your secret identity.

The other important feature of Bitcoins is that there is no centralised coordinator of the Bitcoin records. There is no bank keeping the records. The Bitcoin algorithm is public and information about Bitcoin transaction histories is shared across a peer-to-peer network which allows anyone to independently verify Bitcoin transactions.

It’s a fascinating idea and I don’t know if it will take off. It is only in beta, but there are a number of websites that have begun accepting Bitcoins for payment, as well as sites which will trade Bitcoins for “real” money. I will be watching with interest.

* It really is quite rough, only showing that a secure exchange without key exchanges is possible. Other features, such as authentication and the key asymmetry (either key can lock and then the other key unlocks) are not captured.

Five Down

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One of my favourite blogs is Futility Closet, which is sadly appropriate given its tagline “An idler’s miscellany”. This week it featured a puzzle called Five Down devised by the English mathematician Henry Dudeney. Since the subject of the puzzle is money, it seems like an appropriate one to share here on the Mule.

A banker in a country town was walking down the street when he saw a five-dollar bill on the curb. He picked it up, noted the number, and went to his home for luncheon. His wife said that the butcher had sent in his bill for five dollars, and, as the only money he had was the bill he had found, he gave it to her, and she paid the butcher. The butcher paid it to a farmer in buying a calf, the farmer paid it to a merchant who in turn paid it to a laundry woman, and she, remembering that she owed the bank five dollars, went there and paid the debt.

The banker recognized the bill as the one he had found, and by that time it had paid twenty-five dollars worth of debts. On careful examination he discovered that the bill was counterfeit. What was lost in the whole transaction, and by whom?

I will not reveal the solutiuon here to give you a chance to think about the puzzle. What I will reveal is that the “solution”, originally published in The Strand in 1917, was re-published on the blog yesterday but it is in fact incorrect! Understanding what is wrong with the original solution (and the blog’s author was quick to provide an update following feedback from his readers) gives some insight into two of the roles money plays: a medium of exchange and a store of value.

Banks, Central Banks and Money

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One misconception about the mechanics of money that I mentioned in my last post is the idea that banks can hoard their reserves at the central bank* rather than lending them out.

Here I will explain why this idea simply does not make sense, but no more casinos and gaming chips. No more senior croupiers and casino cashiers. I will dispense with the metaphor and instead stick to a more prosaic explanation, looking at interactions between banks and central banks.

All banks have their own accounts with the central bank. Often these are called “reserve accounts”, although in Australia they are called “exchange settlement accounts” (ESAs). As the Australian terminology suggests, the primary function of these accounts is to facilitate settlement of transactions that take place between banks. To keep it simple here, I will stick to the terminology of “reserve accounts”.

To see how this works, imagine I make a $100 purchase from a shop on my credit card. If the shop banks with the same bank as I do, all that happens is that our bank increases the balance of my credit card by $100 and also increases the balance in the shop’s bank account by $100. With a couple of simple accounting entries and no movement of any physical currency, the transaction is complete. In fact, as was discussed in the casino money post, this simultaneous $100 loan advance to me and $100 deposit raising for the shop has effectively “created” an additional $100 of money in the economy that was not there before.

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