In debt markets we are seeing a catastrophic example of the law of diminishing returns. As Marson makes clear, it takes greater amounts of debt to have the same marginal impact on GDP. The marginal effectiveness of debt has collapsed during the period since the end of the second world war. For the USA, for example, 1 unit of debt generated 0.63 units of GDP between 1953 and 1984; that same 1 unit of debt generated 0.24 units of GDP between 1985 and 2000; since 2000, 1 unit of debt has generated just 0.08 units of GDP.

David Fuller's view For a short, concise tutorial on the long-term risks associated with our government debt mountains, you need look no further than this issue from Tim Price.