In an earlier article I suggested that a currency union does not make market forces go away, it simply diverts them into other channels. It so happens that a customs union is already diverting these market forces into other channels, so there is a shortage of alternative channels left available.
A customs union means that partner economies have no tariff barriers between themselves but have a common external tariff towards non-members, thus in principle creating a single domestic market. Let us assume that Scotland is admitted to (or remains a member of) the EU and that the rest of the UK remains in the EU after 2017. The EU is a customs union.
Whilst the EU single market is not perfect, the RUK and Scottish markets have long been one. Not only are goods and services traded freely between the countries of the UK but workers and capital also move freely.
A larger domestic market enables firms to produce on a larger scale and so make efficiency savings. The result is faster economic progress than the member economies could have achieved separately. However for poorer areas, membership of a customs union comes with a downside. If they can, most people will want to sell goods and labour in places where they receive more for them. This means that for trade between richer and poorer economies to continue in the long term, one or more of three possible adjustments must be made.
- The simplest adjustment is for the less developed economy to run a balance of payments deficit with the more developed. The more developed extends credit to the less developed, effectively transferring funds to finance the continued purchase of its own exports. But a customs union has a single market. Scotland currently has no more meaningful a balance of payments with RUK than Yorkshire has with Lancashire.
- The second possible adjustment is for the poorer country to devalue its currency relative to that of the richer. This makes the poorer country’s exports cheaper and more attractive in the richer country, whilst the latter’s exports become prohibitively expensive in the former. But within a currency union, Scotland’s pound could not be devalued against RUK’s, nor could Scotland's Euro be devalued against Germany's any more than Greece's Euro can be.
- The third possible adjustment is for employment and national income in the less developed economy to fall to a level consistent with its relative inefficiency. Because this depresses the internal economy rather than adjusting the economy's external relationships, it is far more painful and ideally should be a last resort, allowing the two external adjustments to take as much of the strain caused by the imbalance as possible. Unfortunately inside a combined customs and currency union this third adjustment is not the last resort, it is the only resort.
Taken as a whole, the Scottish economy is somewhat less developed than that of England. This is an observation, not a criticism. It is structurally less diverse and hence more vulnerable to swings in the markets for its major industries, a phenomenon exacerbated by a disproportionately large (and currently weak) financial sector and the temporary as well as highly volatile effects of North Sea oil.
The discrepancy between the Scottish and English economies is of course as nothing compared to that between the Greek and German economies. Yet Scotland still needs to take note of what has happened to Greece inside a customs and currency union.
Currently within the UK, the old industrial areas are poorer than the south-east of England, but economies of scale created by our currency and customs unions raise national income sufficiently for compensatory transfers from richer to poorer areas to be politically acceptable. It would be difficult to make such transfers to Scotland after independence.
In summary, I am not sanguine about any of the currency options facing an independent Scotland. Nevertheless, in the event of independence, one of the options must be selected. My judgement would be that a Scottish currency is the least of the evils, but that it requires preparation to start yesterday and much statesmanship from Scottish ministers.