I was in a taxi on Wednesday when we heard on the radio that the consumer price index had risen by just 2.5 per cent over the year to March - smack in the middle of the Reserve Bank's target, leaving it room to cut interest rates further if need be. So, no probs there.
"But why do we have any inflation?" the cab driver asked me. "When I came to Australia I could buy a rock cake for 8¢ - the other day they wanted $3.50."
It was a simple, sensible question. Unfortunately, the answer isn't at all simple. The short answer, however, is that it's a policy choice. That is, the monetary authorities - the central bank and the government - believe a moderate rate of inflation (moderate meaning between 2 per cent and 3 per cent, on average) is, on balance, a good thing.
Inflation refers to a persistent rise in the general level of prices. It may surprise you that in Britain over many centuries there was no net rise in the level of prices. Prices would rise during wars, but then fall back after the war was over. Governments controlled the price level by tying the amount of money in circulation to the amount of gold, and then controlling the amount of gold.
But this "gold standard" broke down during the Great Depression, and after World War II it was replaced by the Bretton Woods system where each country's currency was fixed to the US dollar, with the US dollar fixed to a gold price of $US35 an ounce.
This system meant all other countries effectively imported their inflation rate from the US economy. The Americans kept inflation pretty low until they began financing the Vietnam War by printing money rather than borrowing from the public.
This caused the fixed exchange-rate system to break down in the early 1970s, with most developed countries allowing their currencies to float. This gave them the ability to control inflation for themselves.
The trick, however, is that they - and we - do so not by controlling the quantity of money in circulation (as the monetarists tried and failed to do in the old days), but by using their ability to control the price of money - interest rates - to keep the demand for goods and services pretty much in line with the supply of goods and services. But if the authorities have the ability - in principle, at least - to use their control of interest rates to control the price level, why don't they keep it completely stable, thus allowing a zero increase in the CPI? Why do they permit inflation averaging a couple of per cent a year, and call this "practical price stability" (as they do).
Short answer: because they care about unemployment as well as inflation. The first reason is their belief that, due to practical limitations, the CPI tends to overstate the rise in the price level. Huh? This is because of the delay in including new products in the CPI basket of goods and services, and also because it treats as inflation price rises actually caused by an improvement in the quality of goods in the basket. For instance, part of the reason for the price of the new model Holden being higher than the price of the previous model is that it's a better car - better under the bonnet or better accessories.
If you accept that the CPI tends to overstate inflation then achieving zero inflation as measured by the CPI would involve keeping money so tight you were actually forcing prices down, which would be quite damaging to the economy and employment.
The second reason the econocrats like a bit of inflation is that there can be times when wages grow too quickly and make employing people too expensive. Wages need to fall back a bit, but workers are hugely resistant to cuts in their wages (and sensible employers don't fancy the idea, either).
The thing is that, if there's a positive rate of inflation it's much easier to cut wages in real terms by raising them less than the inflation rate. This is what happens in every recession.
The third reason the econocrats regard a bit of inflation as helpful is that, in a deep recession, they may judge it necessary to stimulate the economy not just by cutting interest rates but by cutting them so far they're negative in real terms - that is, cutting them until they're actually lower than the inflation rate (as they are right now in the US and Britain).
Think it through: when real rates are negative, lenders are actually paying people to borrow from them (after you allow for the effect of inflation), so this should be highly stimulatory. But, clearly, you can't bring about negative interest rates - something you'd only ever do in an emergency - unless you've got a positive inflation rate to go below.
So those are the three reasons the Reserve Bank is satisfied with an inflation rate averaging 2 to 3 per cent and defines this as practical price stability.
But back to my taxi driver. It's all very well to remember how much less you had to pay for things in the old days and feel cheated, but you shouldn't forget your income is also a lot higher than it was in the old days. In fact, just about everyone's income - whether wages or the pension - grows a bit faster than prices are rising, so there's no cause to feel cheated by the system. That is, almost everyone's income has risen in real terms over the years.
This real income growth is the reason economists are so unimpressed by punters and pollies carrying on about the trouble they're having keeping up with "the cost of living". You can achieve that delusion only by focusing on what's happened to the prices you pay and ignoring what's happened to your income.