Keynes has a lot to answer for

Well, that might be a bit unfair. John Maynard Keynes was an exceptionally clever person. It is hardly his fault that people get all confused by what he was saying.

It is an almost undeniable fact that probably more than 90% of the population (maybe more) believe that macroeconomics can be understood by reference to what is nothing more than a basic accounting identity - a banal statement of equivalence:

Y = C + G + I + X - M

Economics begins and ends there for an alarming proportion of the populous and an even more alarming proportion of opinion formers and decision makers (especially my bugbear, "successful businessmen").

Let's get one thing straight. All that little identity tells us is that everything we produce must by definition be bought and/or added to inventories. That is it. There is nothing else in there of use to understand economics, or formulate economic policy.

For example, it does not:

• mean that not buying foreign (imported) goods will increase our output or incomes
• mean that increasing government expenditure will increase our output or incomes
• mean exporting a lot will increase our output or incomes

I could go on, but I think you get the picture. This national accounting identity is just a simplified algebraic description of how we deploy our income. Economics is really (really) about how we create that income in the first place.

So what made me blog this rant today? Believe it or not it was our new IMF overlords in a tangental way. A news report this morning that an IMF paper has floated the idea of a lower income tax rate for women on the basis that they "tend to put more back into the economy than men". And we had a couple of accountants (christ!) and other economic ignoramuses proclaiming what a clever idea. If I had to appraise this argument for its intellectual efficacy I would tend to the technical. Ughhh!! What a load of tosh.

The premise, as presented by the media, is that women will spend more of their income - increasing the "C" in our accounting identity above - hence leading to more output and hence incomes. Output and hence income, we were told, would increase. Huzzah!! We've found the magic formula!!!

Now, it is entirely possible that the IMF report does not make such an argument but that is exactly what was presented and commented upon.

So why is this stupid? It is stupid because if (if) such claims about propensity to consume by the female gender were true, giving them lower taxes than men would reduce growth in our output and incomes. Yes, reduce it not just in one year, but by a small amount every year forever.

To understand why this is so you have to forsake your beloved accounting identity and accept the power of the supply side (mwwaahaahhaaahaahaa).

We create output and hence income by combining labour with capital to create stuff that is greater than the sum of its raw material parts. There are three parts to this process; capital (income we don't consume), labour (blood sweat and tears), productivity (the ingenuity possessed to make stuff out of other stuff).

In market based economies we become wealthier each year because we experience increases in two of those three areas (the amount of labour we have is limited at 24-sleep-eat-etc.). Productivity rises because humans, despite our clear collective stupidity are strangely collectively clever. We become more ingenious as time goes by and can make more stuff and more useful stuff out of less stuff every year.

Then there is capital. This tends to rise over time because we will save some of our income, preferring to defer some of our consumption to later years rather than simply live hand to mouth. That means we have an increasing pot of capital (per head) available to use to produce output and income.

And that is where these spendthrift women come in. If we tip the incidence of taxation towards men and away from women and they do indeed consume more of their income each year, we will reduce the rate at which we accumulate capital. Lower growth in our capital stock means slower growth in our output and hence incomes.

Sure, there will be a lot more bling bling about and we might feel richer, but we will be poorer and the opportunity cost will rise over time as we forsake investment for lipstick.

Do you doubt it? Ireland has just completed a nation wide experiment of this very theory. We consumed and consumed until we made ourselves the poorest country in Europe. We have no capital, that is why the IMF is filling up our hotel rooms.