According to Putnam, what has caused the decline in voting?

Putnam argues that the decline can be explained by the replacement of New Deal voters with the generation that came after them. Generational change and social change are often related. Intracohort change happens within a generation, such as changing music tastes over time. Intercohort change is between generations, and it can transform a society. Social change often involves both of these types. In the case of decreasing political participation, most of the change comes from intercohort change between the generations.