Steven Weldon, "Downsize My Polity? The impact of Size on Party Membership and Member Activism," Party Politics, 12 (July, 2006), 467-481.

First Paragraph:
Scholars have long been concerned with how polity size affects the nature of democracy. Classical theorists, such as Aristotle and Rousseau, praised the small city-state, arguing that it promoted equality, civic virtue and effective citizen participation in public decision-making. In contrast, large polities were thought to engender feelings of alienation, leading citizens to disengage from the political process. In fact, as Robert Dahl and Edward Tufte point out in their seminal work Size and Democracy (1973), the consensus among early political philosophers was that democracy was only viable in small city-states. While the feasibility of large-scale democracy is no longer disputable, scholars continue to debate the effects of polity size on citizen participation and the quality of the democratic process. This relationship has also been a point of interest for students of political parties. In his study of the German Social Democrats, Robert Michels ([1911] 1962) famously argued that larger parties require a more complex organizational structure, and this, in turn, leads to the deterioration of intra-party democracy and eventually to the development of oligarchy. Notably, his discussion on the psychological effects of party size largely parallels classical theorists' arguments about the polity. More recently, Panebianco (1988: 183-203) has sought to refine Michels' theories on party size, organizational complexity and intra-party participation.

Figures and Tables:
Figure 1. Electorate size and party membership enrolment
Figure 2. Party size and member activism
Appendix Table 1. National party membership enrolment and electorate size s

First Paragraph of Conclusion:
This research note has sought to develop a better understanding of a longstanding concern among democratic theorists: how the size of a polity or organization influences political participation. While there are several unanswered questions about exactly how it affects individual-level factors, the evidence shows that increasing size clearly diminishes two types of participation - party membership enrolment and member activism within parties. Yet, in both cases, the relationship is not linear. The effect is strongest among smaller groups and gradually decreases as size increases.