Greg Smith and Dehenna Davison write:

For many in left behind parts of the country, the reality is that the private sector is stifled by a bloated public sector that is almost Soviet-sized in some areas of the North.

This seems to me to be a case of confusing correlation and causality. The reason why the public sector accounts for such a big share of economic activity in some areas is that the private sector in those places is so weak.

In fact, I'd suggest that - for the economy as a whole - a bigger state can work to the benefit of capitalism.

My story here is not about the several mechanisms through which the rich (pdf) disproportionately influence government policy, nor about crony capitalism, corporate welfare, bank bailouts and implicit subsidies, important as all these are.

Instead, let's start in a less likely place - with a paper (pdf) written by Robert Merton in 1969. He showed that the proportion of wealth an investor should devote to risky assets rather than safe ones such as cash or bonds could be described by a simple equation. This says the proportion should be equal to the expected annual return on risky assets over safe ones, divided by the product of the variance of risky returns and a coefficient of risk aversion.

Let's put some numbers into this. One bit of standard theory (p20 of this pdf) predicts that the expected risk premium should be only two percentage points or even less. The standard deviation of a well-diversified equity portfolio is around 15% giving us a variance of 0.0225. And a reasonable estimate of the coefficient of risk aversion is around three. This give us a solution to Merton's equation of 0.02/(0.0225x3) = 0.296. Less than a third of one's wealth should therefore be in risky assets.

For many people, the weighting of equities should be even less. If you could lose your job in a recession, equities are especially risky for you because they too would fall when your earnings disappear. And if you regard housing as an asset (say because you are planning on trading down) it too could fall in a recession, when shares fall. Both risks point to a low equity weight.

What's more, for many people the opportunity cost of holding equities is not cash or bond yields but rather paying off the mortgage or credit card bills, the interest rate on which is higher than that on cash. Yulia Merkoulova and Chris Veld point out that, for these people, the personal equity risk premium is very low or even negative. That can justify holding no equities at all.

Some standard economics therefore predicts that demand for equities should be very low indeed. Which suggests that stock market capitalization should be paltry.

So why isn't it?

Enter the welfare state. The wealth in Merton's equation means your total wealth. Wealth is merely capitalized income*. And income includes pension income. The state pension is therefore a big part of your wealth. At current annuity rates, the basic state pension is worth over £170,000 for a 70-year-old. This means that, following the maths above, somebody with £100,000 of other wealth should have not £30,000 in equities but £80,000.

The state pension thus boosts demand for equities. In giving us a safe income, it allows us to take financial risks we otherwise would not.

Of course, this is not the only way the welfare state supports the stock market. It acts as an automatic stabilizer, helping to mitigate recessions; this is especially important as policy-makers cannot predict recessions and so cannot always use monetary and fiscal policy to stabilize the economy. Such stabilization policy reduces the cyclicality of corporate earnings and also our background risks such as the cyclicality of or jobs and small businesses. On both counts, it raises demand for equities.

We often talk of tax incidence, the fact that taxes aren't necessarily paid by the people they directly fall upon. But there is also benefit incidence: welfare benefits don't benefit only those who receive them, but also those who own the businesses where those benefits get spent.

In fact, there's a third historic benefit of the welfare state. In buying off discontent, it has reduced the threat of revolution which has also supported shares.

All of this explains a big fact - that stock markets in developed economies did best whilst the role of government in the economy was expanding. The UK market made no capital gains on average during the free market era of the 19^th and early 20^th century, but soared in the post-war era.

One reason for the famous equity premium puzzle (pdf) of Mehra and Prescott is that the riskiness of equities fell in the latter part of the 20^th century and so share prices rose - as the threat of depression and political unrest fell. The larger welfare state is a big part of that story.

What Marx said in 1848 is therefore still valid: "the executive of the modern state is nothing but a committee for managing the common affairs of the whole bourgeoisie." The state functions to support capitalism.

Of course, this is not to say that the current boundaries of the state are exactly those which are optimum for capitalism. Reasonable people can disagree on what these are: they might include a lot of social democracy.

Instead, my point is merely that there are many channels through which a big state can - and should! - sustain capitalism. Which is why few intelligent capitalists are minimal state purists, and perhaps why so many rightists have very comfortably abandoned the small state thinking of the 1980s.

* This is why wealth taxes should be redundant. If we're measuring income properly (which the tax system does not), wealth taxes are just capitalised income taxes.