The 2012 NCVO Almanac contained one astonishing figure: the voluntary sector in the UK has liabilities of over over £18 billion. This makes a mockery of the so-called social investment market, making investments worth a couple of hundred million pounds over the last few years. Short term debts, lending from conventional banks and investment directly by individuals massively outweigh the significance of the handful of institutions occupying the emerging social finance space.

But when compared to the levels of debt in the wider public and private sectors, this staggering £18 billion figure becomes a tiny sideshow. To get any meaningful sense of the sector's appetite for debt, we need to look at the ratios - or levels of gearing - between debt and assets, or debt and income. How much is owed in the light of what is earned and what is owned?

First, public sector debt has recently passed the trillion mark - that's over 1000 billion pounds of central and local government borrowing. Public sector assets are also worth around a trillion pounds (so when critics argue that on balance, the public sector isn't worth very much, the numbers appear to back them up!). Debt is higher than annual income, which (garnered from the rather impenetrable ONS figures) appears to be somewhere between half a trillion and a trillion pounds. What's more troubling even is that these debts don't include "financial sector interventions" (aka bailing out the banks), unfunded pensions liabilities or hidden PFI obligations.

Second, private sector debt (and by this we mean business - not financial institutions or private households) is even higher, seemingly between £1.5 and £1.7 trillion. This compares to assets at around £1.5 trillion (so critics of the private sector have even more evidence to fuel their case) and income of around a trillion.

Both sectors, therefore, have outstanding liabilities of around one and a half times what they bring in each year and owe about as much as they own. (Private households and individuals, in contrast, borrow far more than they earn annually but sit on more valuable assets for this risk they take).

And the voluntary sector? Well, NCVO tell us that income is almost £40 billion per year and total assets over £100 billion. With debt at £18 billion, (not including pensions, and much of this owed to short-term creditors) the sector owes less than half of what it earns and a fifth of what it owns. So in financial terms at least, the voluntary sector is an under-leveraged resource, a sector which could take more risk, take on more debt and gear up its activities to a far greater degree.

With trust in financial institutions at an all-time low, business confidence shot and even nation states unable to gain the confidence of investors and markets, is it any wonder that we hear so much talk of the potential of the third sector to take on more investment to solve society's problems? Whether that's really a good idea or not, perhaps depends on your view on why we're in this mess in the first place.