The voters of small, more idealistic parties often feel hard done by. They vote Labour or Green or Progressive Democrat and wonder why that party doesn’t just do what it says it would do, but instead stabs them in the back. In the 1970s and 1980s Labour Party members used to pull their hair out wondering why the parliamentary party just wouldn’t even sound more left wing.
The common claim was that the TDs, once elected, had either sold out or become corrupted by the system.
The answer is actually far simpler. The longer the TDs stayed in the Dail, the more they met the people who voted for them, and discovered something almost unique to Irish politics. That many of their voters voted for them without agreeing with them.
It didn’t apply to FF or FG TDs, because they didn’t really believe in anything specific. But the small party TDs, meeting their constituents, discovered that only a small portion of their voters actually were Labour or Green voters, motivated to vote for them by the party’s ideology. The rest transferred to them for reasons of personal loyalty or constituency work, which meant that the TDs worried more about their fickle non-party voters than the party loyalists, and so became less ideological in the Dail.
If our voting system actually allowed party voters to elect party TDs straight, on a proportional basis, we would probably have less disappointment. Parties would actually have an incentive to remain pure, so as to not lose their pure voters.
But imagine trying to put a coalition together in that climate.