Just a quick thought. Independents are America’s third parties.
Sure, we have nominal third parties: Greens, Peace and Freedom, Libertarians, whatever. But what is missing in America is that huge and periodic wave of third-party entry, of the type that compels governments to change the very rules that got them into office.
It is common to define political parties by their functions: agreeing on some program, nominating people to carry that program out, and stopping people from running who might spoil the election.
Definitions imply measurement. In a party-list-based system, we measure the number of parties by counting them and weighting. In a candidate-based system, we compute the index for candidates instead. We could compute it for parties, but then we would need a decision rule for non-major-party vote shares. Nobody likes to discard data.
One thing going on right now is a hard time stopping people from running. That has been going on for a while, actually. This is why the Commission on Presidential Debates no longer admits candidates — note “candidates,” not “parties” — with less than 15 percent support in five national polls.
Another thing going on is disagreement about program.
The inability of both major parties to (1) agree on program and (2) restrict candidate entry get us two thirds of the way to understanding what just happened in Maine. For those unfamiliar, Maine has changed its voting system to one that accommodates multiple parties. Maine is walking a well-worn path. Before the introduction of proportional voting rules in Western Europe, many countries had made the switch to two-round electoral systems. Was that in response to more parties or more candidates? I don’t know. But going by a functional definition of party, either would reflect the breakdown of existing parties — or, in purely functional terms, more than just two parties.
It also is a functional definition. What happens when existing parties struggle to fulfill their functions? Do they exist at all? Is existence a continuous variable? Are there just more parties? Where are they on the spectrum?