The continued criticism George Osborne is getting for his proposal to limit tax relief on charitable donations highlights something many economists have thought for years - that we should abolish annual Budgets.

Osborne is, of course, not the first Chancellor to have gotten into a pickle such as this; remember Brown's 75p rise in old age pensions and his abolition of the 10p tax band?

The problem is that the tax and benefit system is so complex, and Budgets contain so many different proposals - kaleidoscopes of trivia - that individual chancellors, surrounded by tiny groups of like-minded people, cannot fully anticipate their effects. Bounded rationality plus groupthink equals bad policy-making.

The solution is simple. Budgets should be first words, not last ones. Tax policy should be a matter for consultation, review and deliberations, not for individual statements from on high. The Budget statement should be the introduction of a green paper.

This is, of course, not a new idea. The IFS's Green Budgets are intended to be a model for such policy-making. And we had hoped that when Brown introduced Pre-Budget Reports in 1998 that they would become the start of consultation exercises - though they swiftly became mere mini-Budgets.

Now, I suspect that most of you will regard all this as trivial common sense. However, what's at issue here is two very different conceptions of politics. We have a conflict between politics as rational, deliberative policy-making versus a politics of theatre in which 'great men' determine the nation's economic destiny. It says something about our political system that rationality should be such a radical idea.