Three meanings of intergenerational mobility

We axiomatize three different motivations for being concerned about interge nerational mobility: mobility as a description of movement, as an indicatio n of equality of opportunity. and as an indication of equality of life chan ces. These three motivations are shown to be incompatible. None of the exis ting measures is acceptable as an indicator of equality of opportunity or e quality of life chances. We propose two new measures of intergenerational m obility which more adequately reflect these concerns.