What are they for?

Tweet The statement by Rhodri Morgan and Peter Hain that the Tories were planning to reduce the number of MPs from Wales, and the impact of that on the National Assembly, sparked something of a debate on Syniadau. That debate concentrated more on whether the link between numbers of MPs and AMs had been properly understood than on the principle of a cut in the numbers.

But I'd like to return to the substantive issue, and ask how many MPs we actually need.

Cameron's proposal for a 10% cut seems to be primarily an attempt to make populist capital out of the unpopularity of politicians. The figure of 10% has surely been simply plucked out of the air. But why 10%? Why not 9% or 11% or 20%? And if he really wants to be popular, why not 90% or even 100%? There is no obvious rational basis for the level of cut specified; but then there's no obvious rationale for the current number of MPs either.

Clearly, the apparent over-representation of Wales in numerical terms has been dragged into the debate, along with the suggestion that, as the powers of the Assembly grow, so the need for MPs decreases. I can understand why some would want to suggest that, but I'm not convinced – even when those on my own side support the suggestion.

Our argument for changing our policy on the Second Chamber, and sending peers to London (foolishly and short-sightedly spiked by Brown's pettiness) was based on the principle that we should seek to maximise Wales' voice in any institution making decisions which affect us. At a European level, we have argued that we would more or less triple our representation in the European Parliament as an independent nation-state; and we don't argue in that case that that would be a numerical over-representation.

In many multi-unit states (let's call them federal states), smaller units are deliberately and consciously over-represented. Why wouldn't we want that to be the case for Wales – at all levels?

But I digress – my real point is to ask how we should actually decide what is the 'right' number for the membership of any legislature. The current basis seems to be pretty much arbitrary; based more on 'that's the way it is' than on any rational analysis. In any other walk of life, we'd start from an analysis of what the job is and what the workload is.

So – what are MPs actually for?