In a radio interview recently* I was asked a question to which I could not easily give a satisfactory reply: if the gold market is rigged, why does it matter? I have no problem delivering a comprehensive answer based on a sound aprioristic analysis of how rigging markets distorts the basis of economic calculation and why a properly functioning gold market is central to all other financial prices. The difficulty is in answering the question in terms the listeners understand, bearing in mind I was told to assume they have very little comprehension of finance or economics.

I did not as they say, want to go there. But it behoves those of us who argue the economics of sound money to try to make the answer as intelligible as possible without sounding like a committed capitalist and a conspiracy theorist to boot, so here goes.

Manipulating the price of gold ultimately destabilises the financial system because it is the highest form of money. This is why nearly all central banks retain a holding. The fact we don't use it as money in our daily business does not invalidate its status. Rather, gold is subject to Gresham's Law, which famously states bad money drives out the good. We would rather pay for things in government-issue paper currency and hang on to gold for a rainy day.

As money, it is on the other side of all asset prices. In other words stocks, bonds and property prices can be expected to rise measured in gold when the gold price falls and vice-versa. This relationship is often muddled by other factors, the most obvious one being changing levels of confidence in paper currencies against which gold is normally priced. However, with bond yields today at record lows and equities at record highs this relationship is apparent today.

Another way to describe this relationship is in terms of risk. Banks which dominate asset markets become complacent about risk because they are greedy for profit. This leads to banks competing with one another until they end up ignoring risk entirely. It happened very obviously with the American banking crisis six years ago until house prices suddenly collapsed, threatening to take the whole financial system down. In common with all financial bubbles everyone ignored risk. History provides many other examples.

Therefore, gold is unlike other assets because a rising gold price reflects an increasing perception of general financial risk, ensuring downward pressure on other financial asset prices. So while the big banks are making easy money ignoring risks in equity and bond markets, they will not want their party spoiled by warning signs from a rising gold price.

This is a long way from proof that the gold market is manipulated. But the big banks, and we must include central banks which are obviously keen to maintain financial confidence, have the motive and the means. And if they have these they can be expected to take the opportunity.

So why does it matter if the gold price is rigged? A freely-determined gold price is central to ensuring that reality and not financial bubbles guides us in our financial and economic activities. Suppressing the gold price is rather like turning off a fire alarm because you can't stand the noise.

*File on 4: BBC Radio4 due to be broadcast on 23 September at 8.00pm UK-time and repeated on 28 September at 5.00pm.