THE RECENTLY completed Carnegie Corporation-sponsored report on the aging society begins by asserting that “the inexorable aging of our population” is a demographic revolution that “will affect every individual and every institution in the society.” This remarkable transformation in age distribution is clearly borne out by the data: The proportion of the American population over age 65 tripled between 1900 and the present (from 4 to 12 percent), and it is projected nearly to double again between now and the year 2050 (from 12 to 22 percent). The effects of this pattern lead us to ask the crucial question of whether the arrangements for supporting the older population that have evolved over the past fifty years can or should be maintained.