In this book I seek to explain party position change in American politics. Although every issue is unique, my contention is that we can generalize about the process of parties' development of positions to a great extent. Close inspection reveals that similar dynamics are evident in very different issue areas. The argument I make is about the interaction of parties, issues, and groups. It is also focused on parties' relative positions on issues. All these terms can be used in different ways for diverse purposes. So before proceeding to an elaboration of theory, cases, and evidence, I define the key concepts I employ. I also explain my focus on parties' relative positions on issues.

WHAT IS A PARTY?

American political parties are notoriously poorly bounded institutions. Unlike parties in most democracies, they have no formal membership. Party registration exists only in some states and is managed by state governments. The parties themselves do not admit and expel members, unlike any true membership organization.

As a result of these fuzzy boundaries, scholars have long disagreed over basic questions such as “what is a party?” and “who runs parties?” Two pioneering students of American parties, V. O. Key and E. E. Schattschneider, differed over whether voters, even those who supported a party’s candidates, registered under its name, and voted in its primaries, could usefully be seen as part of the party.