In political campaigns, as in more violent forms of warfare, many battles are decided before the first shot is fired. One side comes to the field with such advantages that the result is preordained. There was never any question that Tony Blair was going to win the general election of 1997 just as there was little serious doubt that Margaret Thatcher would triumph in the election of 1987. The campaigning in those instances was a lot of sound and fury which signified almost nothing. It didn't make any fundamental difference to the outcome.

The referendum on electoral reform, the first nationwide plebiscite in Britain since the vote on the Common Market 35 years ago, is an exception to this rule. This is a battle in which the campaign really will matter. Talk to people on the no side and there is one thing on which they agree with strategists in the yes corner. This one could go either way. There is everything to play for in the 11 weeks between now and the moment of decision.

Most voters have yet to engage with the arguments. I belong to that tragically nerdish minority who are fascinated by electoral systems and think they can make a significant difference to the quality of politics and governance. Perhaps you too are a member of this small club of saddos who enjoy teasing out the rival merits and demerits of the single transferable vote versus the additional member system. Most of our fellow citizens have, meanwhile, been getting on with their lives, blissfully unaware that debating the pros and cons of different electoral systems can be better than sex.

Several consequences flow from this. One is that current opinion polling is highly unreliable as a predictor of the eventual outcome. An unusually high proportion of people are in the "Don't Know" category. Of those who say they have formed a view, many may be persuaded to change it. Support on both sides is soft. Those campaigning for a change to the alternative vote reckon this can be good for them. The more the public learns about the attractions of being able to rank candidates in order of preference, the more people will like it. The defenders of "tried" and "traditional" first past the post believe that when people are uncertain about whether or not to make a change, they are more likely to cleave to the status quo. That is why their campaign messages are so very negative. They seek to foment fear of change by depicting AV as confusing, scary and foreign. If you could have a penny for every time you will hear an anti-change campaigner scoff that AV is used in Papua New Guinea, you will be a billionaire by the time this battle is done.

The yes campaign will seek to frame this referendum as a once-in-a-generation opportunity for the people to set new rules for the political class. It was on this theme that Nick Clegg majored during his speech on Friday. He attributed the parliamentary expenses scandal to the way in which first past the post gives seats for life to many MPs. He threw in earlier scandals, cash-for-coronets and cash-for-questions. I'm sceptical that AV is the miracle cure which will purge us of every lazy, disconnected or corrupt MP, but as I've argued here before, I do think it would be a fairer and more appropriate electoral system for contemporary Britain. It will be a worthwhile improvement if MPs have to gather some form of support from at least half of the voters. The parties will be impelled to engage with more parts of the country than just a minority of marginals and it will pay MPs to connect with more parts of their constituencies.

David Cameron did not really engage with this strand of the case for AV when he spoke on Friday. That speech was not among his best. Those in his party who are paranoid about Mr Cameron's long-term intentions will rumble that this is because his heart really isn't in it and he privately wouldn't mind that much if AV wins because it would strengthen the coalition and make it easier to strike another deal with the Lib Dems at the next election. Some of the Tory right are trying to goad the prime minister to campaign more aggressively and throw all the might of his party machine behind the no campaign. They are trying to turn the referendum into a virility test for the prime minister by suggesting that a defeat for first past the post will be a colossal personal humiliation.

I think the speech wasn't that good because the case for retaining first past the post is so uncompelling. The no campaign in general has almost nothing to say which is positive about the status quo. Its arguments are negative ones against change. Mr Cameron took the same approach. Under AV, he contended that "hung parliaments will become commonplace" which will lead to more "haggling" and "stitch-ups".

Being a clever chap, who studied electoral systems at Oxford, he knows this is disingenuous and not only because he is usually to be found singing the praises of the coalition over which he presides. AV will, at most elections, distribute seats a little more fairly than first past the post, but AV is not a proportional system. It is a majoritarian system. If there is a strong national will to award a majority of seats in Parliament to one party, AV will do that. Australia has used AV for more than 90 years. It has resulted in just one hung parliament in 38 elections. First past the post in Britain produced hung parliaments last year, in February 1974, in 1923 and 1929 and twice in 1910. It has also produced parliaments which became as good as hung after the elections of 1950, October 1974 and 1992.

The worst argument advanced in the prime minister's speech was that AV is too complicated. He said: "I don't think we should replace a system that everyone gets with one that's only understood by a handful of elites."

Well, let us accept that numbering candidates 1, 2, 3 does require a slightly more advanced level of numeracy than simply making a cross. I think Britain will cope. Many Britons already use AV when electing representatives for charities, churches, companies, trade unions, societies and voluntary organisations. Labour and the Lib Dems both elect their leaders by AV. Funnily enough, ever since the 1960s, when the Tories started to elect their leaders, they have used either AV or a close cousin. Had they used first past the post in their last contest, the leader of the Tory party would not be David Cameron. It would be David Davis.

Australians have managed to master AV. The prime minister is surely not suggesting that the fine people of Britain have a lower collective IQ than our friends in the Antipodes?

While his speech did not muster any fresh arguments in favour of first past the post, it did draw attention to the general attitude of the anti-reformers. Their propaganda puts most weight on this contention that AV is just too taxing for the poor old British voter to get his or her head around.

The no campaign will probably not put it so indelicately themselves, but they are calculating that their best hope of preserving first past the post is to mobilise what you could crudely call the Thicko Vote. This explains a very revealing switch in their tactics.

A few weeks ago, you may recall, the antis were loudly complaining that it was wrong to hold the referendum on the same day as the elections for local councils and the devolved governments in Wales and Scotland. It was monstrous, they cried. It was damn near unconstitutional, they yelled. The no men in Parliament attempted to amend the legislation to separate the referendum from the May elections.

Have you heard them making that argument recently? No, you haven't. Not a peep from them. Here's why. They've now had a look at what type of person is more likely to agree with each proposition. The polling suggests that AB voters, the more affluent and generally better-educated segment of the population, are more inclined to support reform. DE voters, by contrast, are more likely to be persuaded that we should stick with the status quo. If the turn-out is low, the DEs will be the ones staying at home. So the no campaign now believe it suits their cause that the referendum will be on the same day as the May elections because that ought to boost turn-out.

We will see whether they are correct in this cynical calculation that the British can be persuaded that they are too dimwitted to be able to count to three. Whether or not they know it, many millions of Britons already have extensive experience of using preferential selection because they have been regular voters in Big Brother, Strictly Come Dancing and The X Factor. They not only understand this form of voting; they enjoy it. The no campaign assumes nevertheless that they are incapable of writing 1, 2, 3 on a ballot.

Does the campaign to keep first past the post think that most Britons are stupid? Yes. Not only that, they are relying on the stupid vote to win.