2 step for the Bank, doe see doe your partner, yeah!
I have to say, I like the level that the discussion has just gone to, which is way up, a quantum step up, as it were.
As far as possible instabilities that are inherent in the banking system goes, I think there could be two main contributing factors that might even in themselves be causes of instability. I am curious on how both you Startz, and you psionl0, will think about them, so here goes.
1. "
The host government of a central bank goes into an impossible contract when it gets loans. These loans 'infect' other loans that normally have at least the theoretical ability to be repaid, and are thus, not impossible contracts initially, but become practically impossible by the infection. The more loans that get infected, the more unstable the banking system becomes until too much instability occurs, causing bank runs and other problems."
Now, hold your breath for a second, I know this sounds wooish as all hell, let me present this in terms of assets and liabilities and maybe this can be borne out by analysis. First off, let's be honest, the central bank of a particular country (or countries with ECB), does not have to play by generally the same rules as commercial banks do.
The main thing central banks do not have to worry about is reserve and asset ratio requirements is what I am pointing out here. So if in the balance sheet for a central bank that I present to you seems like it has scary numbers as per those kinds of requirements, don't worry too much about them (unless that is, you know about something I do not, which is entirely possible).
OK, so the first thing I will try to do is create an impossible contract. I want to distinguish between impossible in theory, and impossible in practice. Impossible in theory is a much stronger form of impossibility. In this case, the mathematics is such that a given condition can not be met (since we are talking about loans, it will be the impossibility of repaying a loan using the mechanisms available in the system). Impossible in practice means that while it may be possible in theory, certain practices exist that make it pretty much impossible for something to happen (a poor person not ever getting a job, thus making it impossible in practice for the poor person to pay off a loan the person has).
So we start off with a central bank that has nothing. I will do the no capital case first because it is the one that most clearly shows an impossible in theory loan contract. So, then the central bank makes a loan to it's host government of X. The balance sheet should look like so if I understand correctly how to do balance sheets.
Central Bank of Moneystan
Assets:
Reserves: 0
Loans: X
Liabilities:
Deposits: X
Capital: 0
Now, I am on purpose trying to make a theoretically impossible contract to fulfil, just to show it is possible, and how the impossibility works. If the Central bank of Moneystan wants in return for the loan, any interest at all, the above is an impossible contract. This is because, quite simply, there is not enough in Deposits to pay for what is in loans
and the interest that is owed. The only thing Moneystan could do is get yet another loan, which would only compound the problem, but allow for the debts incurred to at least still be serviced.
Now, the real case is probably more complicated. The central bank should have no reserves however, because reserves is what a bank has on the books with a central bank. There should be something like capital for central banks though, so it is possible with capital, that if there is enough capital, the loan may be repaid.
What of infection though? I am not too certain what I mean by this. Normal bank loans should at least be theoretically possible to be repaid (I used to not think this, but now I see that this is the case). From what I understand, in the US for instance, pretty much all of the taxes that go into paying off the national debt go towards interest, with none left over to pay off the principal. If that is the case in the country of Moneystan, then for every new loan made by one if its banks (not the central bank), there will part of it that has to go toward servicing the interest on the national debt.
The part that goes toward servicing the national debt interest means that those loans are now 'infected' by an impossible debt contract (whatever part is used to service the national interest can not be used to paying the loan principal and interest because of taxes). It gets more interesting when you consider the consequences of the national debt interest also not being completely repaid.
If the interest is not serviced (like a person with a credit card paying only the minimum payments but then not even paying that), then the problem becomes the dreaded compounding interest problem (exponential functions away!). This exponentially rising interest at first remains serviceable because Moneystan just goes more in debt, but after a while, the other loans become so infected, the whole system comes crashing down.
2. "
The wealth and stored labour value of society flows out to banks through Rentier mechanisms described as per Henry George, thus leaving not enough left for society to ensure stability, resulting in instabilities to the banking system."
I love that word, rentier, pronounced, ron - tee - ay (not rent - ear or ren - teer). Add in some French Physiocrat frillage and I think you will have the right pronunciation. So, the idea is somewhat encapsulated in the above sentence if you have the right background knowledge, but I think it is worth spelling it out even if you know about Henry George and his work.
I am definitely not an expert on Henry George or the Classical Economists, so I am probably going to mess up this explanation to one degree or another. Let me see if I can get the right outlines of the idea, at least.
First, a quick outline of Henry George terminology, as well as one basic idea. First the terminology. Land is any natural resource. The profits due to owning land are called rents. Capital is anything that is man made (I will possibly be using the term capital interchangeably with capital of a bank or even as a different term for money, but these are different. I do disagree with Henry George's idea that one should classify money(capital) the same as capital defined as described before for what capital is, because while money is made from human labour, perhaps even represents human labour, there is another non-capital aspect to money that I think he missed about money, and that is it facilitates trade). So, after that long detour of a parenthetical remark, profits earned from capital is interest. Labour is human work. The profits of sin may be Eternal Damnation (naw!), but the profits of labour is a wage.
Now that that is out of the way, one more Georgist type idea. Land (as in, normal land, the good earth, or some cube of air on it) gets it's value from development near the land. Land in the city is more valuable than in the countryside, that sort of thing. Well, that additional value comes from the community around a given piece of land. More on the implications of that in a second.
This is connected to something banks are also want to do. Banks make loans to real estate investors. What a real estate investor will do at least some of the time (and especially during boom periods) is take a loan from a bank such that the interest is covered by the rental value of the land the investor purchases with the loan. Then the investor sits on the loan for a while, waiting for the price of the land to go higher. Once it is high enough the investor sells, pays back the loan and gets a profit based on the difference in the form of capital gains.
Who is getting what in this deal, as well as how, is the question I will address next. The bank is getting the rent! The classical economists all said they wanted a free-market. Well, a free market is one where rents have been reduced as much as possible (the modern day definition of free market is almost the same as free for white collar criminals not to go directly to jail and not collect $200 for going around the board. Which makes me recall that the game of Monopoly(TM) was originally created to explain this rip-off to everyone, maybe that is why everyone hates playing that damn game! Maybe they should have a new game called Rentier that includes FRB banking, that would really blow some minds (if they could be expected to follow the rules (I know the current banking system can't seem to))).
This is therefore
not a free market, as it is not free of rents. The bank in the end (or it's shareholders), gets the rents. They are the end of the rentier chain. The investor on the other hand gets something else. They get the upswing in value created by the community where the land is located. So banks siphon off rents, real estate investors siphon off community investment. Real good deal for both, crappy for everyone else.
Now, when enough siphoning occurs, the end result is that reinvestments that should occur for the upkeep of society, do not occur. This leads to broken roads (the US has an F rating on its infrastructure, I have read, maybe I could find the specific reference if needed), a loss in jobs because capital is not being reinvested, etc. etc., eventually leading to an unstable economic situation in various ways depending on if we are in a boom or a bust period.
My take? I do not know. It could be a combination of 1. and 2., with maybe something else added in, that leads to these instabilities. I thought it would be fun to at least introduce these kinds of ideas for discussion purposes.
I will say one thing for sure, it certainly seems to matter economically if you are the one putting money into the capital of a bank, or the one on the receiving end of capital from a bank (unless you are one of those stupid smiling bank tellers that are always so ridiculously happy all the time)!

All the best to you all!