That is undoubtedly what readers of Matt Yglesias' blogpost on immigration and retirement income are saying. Matt correctly notes that an economy cannot collectively save for a generation's retirement in the sense of putting aside the goods and services that the generation will consume in retirement. His conclusion is that we need large numbers of new workers to support our current or soon to be retired population. This leads him to call for a much larger number of immigrants.

While we may want more immigrants, the need to support a larger retired population should not rank high on the list of reasons. According to the Social Security trustees projections, a more rapid pace of immigration will make little difference to the program's finances. This is due to the fact that immigrants will also get benefits. Since they tend to work for lower pay during their working lifetime, and the program's payout structure is highly progressive, the net gain from more immigrants is limited. Increasing the projected immigration level by 30 percent reduces the projected long-term shortfall by less than 10 percent.

On the other hand, suppose that real wages grow roughly in step with productivity. If we saw real wage growth of 1.5 percent annually, then the tax increase needed to meet the projected 75-year shortfall would be equal to 4.6 percent of projected wage growth over the next 30 years. Suppose we got real kinky and imagined we saw some of that 2.0 percent annual wage growth that we had in the golden age (1947-1973). Then the tax increase need to main the program's solvency would be equal to just 3.2 percent of projected wage growth over the next 30 years.

The story here is straightforward. We expect retirees' income to be related to their living standards in their working lifetime. If wages grow rapidly then it is easy for a smaller number of workers to support a growing population of retirees while still ejoying a rise in living standards. This is the way the world used to work. It might not be easy for political reasons to get back to that world, but we should at least know that such a world did once exist and is still possible.