The Robin Hood campaign rumbles along. And, I'm afraid to report it's not all plain sailing for our merry band of bumbling wannabe tax experts. Although the concept of a tax that could raise $400bn out of thin air seemed to go down well with a willing, indebted public, it's not looking so great under the spotlight of economic opinion.

There's a thread over on the Robin Hood site ostensibly called Doubters' questions answered but which actually does nothing of the sort. The contribution by Cantab83 is particularly brutal.

That particular doubter's questions have been met with a telling (yet honest) response: "Er, we'll get back to you on that..."

I have a question of my own too. A common criticism of the banking sector is that it's a zero sum game. Yet the Robin Hood Tax believes it can raise $400bn from this zero sum game. Just like double-entry book-keeping, you simply can't take money out of one side of the equation without affecting the other.

So, instead, let's assume the zero sum hypothesis is wrong. This would mean banks' operations are in fact creating value. Shouldn't we be stopping to wonder whether we would get more value out of leaving them be instead of taking the money out?

People who read this post also read:

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• Who gained from the crisis?
• Murphy thinks the bank supertax worked
• Murphy’s mate admits tax incidence point

Filed under: Current issues, Economics, Other blogs with tags banks, deficit, robin hood, tobin tax