Stories like this or the debate over social security suggest to me that the basic idea behind defined-benefit pension plans is fundamentally brittle. All of th

Stories like this or the debate over social security suggest to me that the basic idea behind defined-benefit pension plans is fundamentally brittle. All of the variables feeding into a pension fund's balance sheet - market fluctuations, new contributions, the duration over which an individual will ultimately receive payments, etc - are fundamentally unpredictable. I'm not sure what kind of machine it would take to take all those inputs and output a reliable stream of fixed-size payments, but I suspect that magic would be a key component. Maybe it was easier during the period where pensions became so popular in the US. Fluctuations presumably aren't so problematic when the upticks greatly outweigh the downticks, the 5-10 year trend always has a positive slope, and you aren't getting ready to have 1/5 of your workforce hit retirement age all at the same time.