In Chapter 4, we analyzed Macropartisanship as the aggregate partisanship of the entire electorate. When Macropartisanship moves, however, voters do not all move in tandem. Some groups may undergo more partisan change than others, or even move in opposite partisan directions from each other. Moreover, with some entering the electorate and others exiting, the very composition of the electorate is always changing. Every 60 years or so, the population of adult citizens gets entirely refreshed as new citizens replace the old. We should not mistake the shifting partisanship of different generations for partisan conversions among a constant set of citizens.

We have not had much to say about demographic divisions or changing electoral composition thus far. Indeed, the consistent strategy of our enterprise is to ignore differentiations of all kinds and ask what we can learn by focusing solely on variations that occur over time. That is what we have done with partisanship in the previous chapter. Although we have stopped short of asserting the point, the implicit message of that chapter is that distinctions are unnecessary, that the movements that matter happen to the whole electorate over time, not only for certain demographic groups or certain political generations.

An alternative view is that not only does partisan movement vary by group or generation, but indeed that by focusing on such distinctions we can explain the movements we ascribe to the whole electorate. Thus, for example, the Republican resurgence of the 1980s is a descriptive fact.