In a properly functioning parliamentary democracy, voters can do much more than cast a vote from time to time. They should be able to hold their government to account and, if they decide they don't like it, replace it with another - in effect, a government in waiting.
If the system works well, that government in waiting will have been identified in advance, and the voters will have had the chance to compare what it offers in prospect with what has been delivered by its predecessor.
It doesn't always work like this, of course. In some systems, the voters find it hard to get rid of the government, let alone identify a credible successor. In post-war Italy repeated elections were held but voters could never get rid of the Christian Democrats, not because they were so popular but because the opposition parties were so fragmented.
It was often said - with some justification - that this was a particular weakness of proportional representation systems. But it has been the particular genius of New Zealand voters that we have managed to secure through MMP the advantages of a more representative Parliament without losing the essential choice between right-of-centre and left-of-centre governments.
There is a further advantage of a system which produces credible competing contenders for office. It usually compels the contenders to vie for the support of centre or uncommitted opinion. It is, in other words, a force for moderation in our politics.
That, at least, is how it should operate. But, in the US at present, we see the opposite - an instance of one of the two major parties being taken over by an extreme minority and abandoning the battle for moderate opinion.
In New Zealand we have no such concerns. Despite the occasional (and somewhat ridiculous) charge that the opposition to the present Government has moved to the "far left", we have succeeded in maintaining the battle for the centre as an essential element of that quintessential democratic power to vote one government out and another in.
Yet those aspects of our democracy can't be taken for granted. If our system is to produce its full benefits, it depends on there being a credible alternative to the party in power. An effective democracy depends, in other words, almost as much on the opposition coming up to scratch as it does on the governing party.
With Labour and its potential allies languishing in the polls, the political battle had been a bit of a phoney war. The Government could afford to take a fairly cavalier attitude towards other views and to public opinion in general. They were able to convince themselves that the absence of a credible alternative meant the next election was in the bag.
That's why while supporters of the present Government may take a little convincing, the emergence of a credible Labour-led Opposition - a credible Government in waiting - is something to be celebrated by all democrats.
We now have a real choice. It's no longer enough for John Key to smile while coasting and ignoring public opinion. We have a real clash of ideas.
With Labour not only proving itself to be an effective Opposition, but also offering an alternative agenda for the country's future, there is now an opportunity for voters to think about real politics - and that's how it should be.
The result is likely to be better and more responsive government in the run-up to the election. Ministers will need to think harder about the rationale for their policies and the interests of those who may be disadvantaged by them. They'll have to take into account not just the views of their own committed supporters but of a wider spectrum of opinion as well.
Voters will have to work harder, too. They will be challenged to go beyond the superficial and make a proper evaluation of competing views as to where the country's interests lie. Should the Government's belief that advancing business interests produces the best outcomes for the rest of us be supported, or should we pay more attention to the interests of ordinary people?
So hold on to your hats. The phoney war is over. It's now game on.
Bryan Gould is a former UK Labour MP and former vice-chancellor of Waikato University.