En politiskt kontroversiell fråga rör hur statens storlek påverkar den ekonomiska tillväxten. Politiker på vänsterkanten brukar hävda att nya statliga satsningar av olika slag har förmåga att lyfta ett lands ekonomi; politiker på högerkanten brukar istället hävda att sådana satsningar och de högre skatter de tenderar att medföra hämmar ett lands tillväxtpotential. Vad säger egentligen forskningen? En ny översikt av Andreas Bergh och Magnus Henrekson, ”Government Size and Growth: A Survey and Interpretation of the Evidence”, accepterad för publicering i Journal of Economic Surveys (preliminär gratisversion här), finner följande:

The literature on the relationship between the size of government and economic growth is full of seemingly contradictory findings. This conflict is largely explained by variations in definitions and the countries studied. An alternative approach – of limiting the focus to studies of the relationship in rich countries, measuring government size as total taxes or total expenditure relative to GDP and relying on panel data estimations with variation over time – reveals a more consistent picture. The most recent studies find a significant negative correlation: an increase in government size by 10 percentage points is associated with a 0.5% to 1% lower annual growth rate. We discuss efforts to make sense of this correlation, and note several pitfalls involved in giving it a causal interpretation. Against this background, we discuss two explanations of why several countries with high taxes seem able to enjoy above average growth. One hypothesis is that countries with higher social trust levels are able to develop larger government sectors without harming the economy. Another explanation is that countries with large governments compensate for high taxes and spending by implementing market-friendly policies in other areas. Both explanations are supported by ongoing research.

Överlag ett negativt tecken på sambandet, alltså. Som påpekas ovan är dock kausalitetsfrågan svår att klargöra:

[A]lthough there is close to a consensus on the sign of the correlation, there is also consensus on the fact that causality is very hard to establish with certainty using the method of instrumental variable estimation – or any other method currently available. … The main lesson to be learned from exploring these important mechanisms is that a negative coefficient on government expenditure in growth regressions need not imply that large government causes slower growth. On the other hand, a negative coefficient on taxes actually provides rather strong evidence that high taxes cause lower growth, because reverse causality leads us to expect a positive correlation.

När det gäller hur högskatteländer som Sverige kan växa så pass bra tycker jag om de två förslagen till förklaringar. Författarna skriver t.ex.:

It seems likely that many reforms in Sweden in the 1980s and the 1990s compensated for the negative effects of high taxes. The Scandinavian countries … also have relatively high levels of economic freedom.

Detta är i linje med Richard Posners tolkning, och jag finner den själv rimlig. Frågan är: Med lägre skatter på arbete, som Sverige har fått på senare år, har inte landet potential att växa ännu bättre?