It's common to hear that governments need to be close to the people, and therefore smaller. It's equally common to hear that inconsistencies across borders are a problem, and so governments need to be larger (globalisation is often mentioned at this point, not always in a logically sound way).

One solution to this problem is to separate the functions of policy and administration, having a large jurisdiction legislature and setter of policy, and many small-scale administrative regions. This produces an obvious problem when the two levels of government disagree, since the line between the administration of policy and the policy of administration (to borrow from Jay & Lynn's Yes Minister) can be fine.

Suppose we are trying to get along with one level both for administration and for policy? What size whould the units be? Obviously the answer depends on the governmental function, and we will almost certainly end up wanting more than one level of government. But we don't want to have every possible level of government. So which ones do we need, and which can we do without?