Similarly, Sweden has a smallish population (some 9.5 million) with a long history of economic and social population measurement (legibility in James C. Scott's terminology in Seeing Like a State). I see more and more research out of Sweden answering sociological questions based on rigorous measurement. Examples: An amazing amount of assortative mating within psychiatric disorders, Deinstitutionalization, Sweden edition, Feminists and unexpected field experiments, and Behaviors and well-being.
In that pattern of research there is Inheritance and wealth inequality: Evidence from population registers by Mikael Elinder, Oscar Erixson and Daniel Waldenström. From the abstract:
This study estimates the effect of inheriting wealth on inequality and mobility in the wealth distribution. Using new population-wide register data on inheritances in Sweden, we find that inheritances reduce inequality and increase mobility among heirs. Richer heirs indeed inherit larger amounts, but less affluent heirs receive substantially larger inheritances relative to their pre-inheritance wealth than do richer heirs. The Swedish inheritance tax had a small overall impact but appears to have mitigated the equalizing effect of inheritances. We also investigate the potentially confounding role of pre-inheritance gifts and behavioral responses to expectations about future inheritances, but neither of them change the main finding that inheritances reduce wealth inequality.If true, and if true in countries other than Sweden, this is a quite interesting caution agaiinst following logical assumptions without checking against actual demonstrated facts. It is logical to assume that inheritances would increase income inequality in a population. It makes so much sense. And if it were the case, then that in turn provides an excellent rationale for increasing inheritance taxes. High inheritance taxes could be assumed to reduce inequality, an emotionally appealing idea.
But emotions should be held in check by evidence. The Swedish evidence suggests that if income inequality is your main concern, then removing inheritance taxes is a good public policy approach.
There is a jaundiced view that inheritance taxes are actually a scheme by the established elite to bar the middle class from entering the elite class and that reducing inequality was never the objective in the first place. The argument is that the established elite are in a position, having sponsored the policies in the first place, to find the loopholes to protect their favored status while the actual burden falls most heavily on the middle class. Under this scenario, you keep out the hoi polloi and raise money on someone else's labor at the same time. A win-win for the the vested interests.
Regardless for the original justification, the actual data from Sweden suggests that high death taxes do not facilitate reduced income inequality.