"[T]he public-pension industry -- government unions and the various financial and actuarial consultants employed by pension-plan managers -- claims that 'transition costs' make switching employees to defined-contribution pensions prohibitively expensive. Fear of 'transition costs' has helped scuttle past reforms in Pennsylvania, as in other states.... [But] nothing requires a closed pension plan to pay off its unfunded liabilities rapidly, and there's no reason it should. Unfunded pension liabilities are debts of the government; employee contributions are not used to pay off these debts. Whether new hires are in a defined-contribution pension or the old defined-benefit plan, the size of the unfunded liability and the payer of that liability are the same."