- Se (R&R) estão certos (no sentido em que países com dívidas públicas acima dos 90% têm o crescimento comprometido), então Portugal, cuja divida pública está agora nos 107% do PIB, não tem nenhumas condições de voltar a ter crescimentos acima dos 2% durante esta década, o que agravará todos os nossos problemas.
Correlação não é casualidade, mas depois de explorarem os dois sentidos possíveis, R&R concluem pelo sentido endividamento causa baixo crescimento, e retiram da análise importantes consequências sobre políticas económicas:
- For many if not most advanced countries, dismissing debt concerns at this time is tantamount to ignoring the proverbial elephant in the room.
Krugman, num post de agosto de 2010, é um dos que levantou dúvidas sobre a causalidade sugerida por R&R entre dívida e crescimento (no sentido de que a causa de uma nível elevado de dívida é a causa de um baixo crescimento da economia), e salienta a importancia que esses trabalhos têm tido na construção das políticas pró-austeridade:
- In practice, the article has been widely used to claim that there’s a red line of 90 percent in the public debt to GDP ratio that one crosses at one’s peril.
- To answer the question "Do high levels of public debt reduce economic growth?" we follow the econometric procedure of trying to reject the proposition that “debt has no growth effects”. Our research shows that this proposition cannot be rejected, so it may well be that it is true. We cannot, however, be sure.
- we do not find any evidence that high public debt hurts future growth in advanced economies.
- Therefore, given the state of our current knowledge, we believe that the debt-growth link should not be used as an argument in support of fiscal consolidation.
- Our reading of the empirical evidence on the debt-growth link in advanced economies is:
- There are many papers that show that public debt is negatively correlated with economic growth.
- There is no paper that makes a convincing case for a causal link going from debt to growth.
- Our new paper suggests that such a causal link does not exist (more precisely, our paper does not reject the null hypothesis that there is no impact of debt on growth).
- The fact that we do not find a negative effect of debt on growth does not mean that countries can sustain any level of debt. There is clearly a level of debt beyond which debt becomes unsustainable, and a debt-to-GDP ratio at which debt overhang, with all its distortionary effects, kicks in. What our results seem to indicate, however, is that the advanced economies in our sample are still below the country-specific threshold at which debt starts having a negative effect on growth.
O prognóstico de Nicolau Santos pode não ser tão inevitável como sugere, pelas razões que sugere.
Mas se a causalidade afinal for reversa (ou seja: se o endividamento elevado for causado por baixos crescimentos) então o que está a acontecer em Portugal, e não só, é verdadeiramente catastrófico e criminoso: à procura de reduzir à força e à bruta o deficit público está-se a provocar uma forte recessão economica, com crescimentos negativos da economia, de que resultará então um inevitável aumento da dívida pública, então para níveis totalmente insustentáveis.
Atualização, 28 Julho 2012: Martin Wolf faz uma relevante discussão das teses de R&R sob o ponto de vista de política económica, em Objections to providing fiscal support for deleveraging no seu blog no FT. Apesar de pouco desejavel, a divida publica pode não ser tão indesejavel ou perniciosa como querem fazer crer, em especial em situações de "liquidity trap".
- It is therefore quite possible to get out of debt by going into it, because they are not the same debtors. And the distribution of the debt, not its level, is what matters.
- the conclusion one cannot draw is that public debt must be kept below 90 per cent of GDP, whatever the cost. Struggling to keep debt below 90 per cent of GDP might be far more costly than letting debt rise above that threshold.
- The authors probably do not wish to argue that the UK should not have fought World War II because it led to excessive public debt (peaking at close to 250 per cent of GDP).
- Again, if the government’s borrowing was aimed at reducing the economic impact of private sector deleveraging, the economic costs of keeping debt below 90 per cent, instead, could well exceed the costs of allowing debt to rise above it. The authors do not analyse such counterfactuals.
- In the case of Japan, for example, it seems quite plausible that a collapse in growth opportunities after 1990 also lowered investment opportunities. This then generated long-lasting financial surpluses in the corporate sector, whose counterparts were high fiscal deficits. The causality would then indeed go from poor growth opportunities to high public debt, rather than the other way around.
- Again, let us accept that very high public debt ratios may create problems. None the less, the period after the Napoleonic War was when the UK began its industrial revolution and the post-war period was one of good economic performance, in both the US and UK. The conclusion is that high debt can be perfectly manageable in countries that know how to manage it.
- It is all about timing. While the private sector is deleveraging and so running large financial surpluses, large fiscal deficits are necessary, provided they can be sustained, as they certainly can be in the US. Once the deleveraging is finished and the economy recovers, the fiscal deficit will need to be closed. The key is to introduce policy commitments on taxes and spending that make a closure of the deficits credible.