Why would a prime minister with a two-thirds majority in the lower house of parliament go to the polls two years early? While Abe's Liberal Democratic Party (LDP) is experiencing a slump in the polls at present, it is two years away from having to front the electorate if the normal electoral cycle is followed. If we scratch the surface it is not difficult to find reasons why Abe has taken this extraordinary step. But what really needs explaining is why Abe is risking so much in the process.

Abe's justification for the snap election is to seek a mandate to delay a planned increase in the consumption tax from 8% to 10%, originally scheduled for October 2015. This is a flimsy excuse indeed, given the LDP's overwhelming majority in both houses of parliament. The Government can revisit the consumption tax legislation and get it through whenever it pleases.

The real incentive for Abe here is to placate the party's rank and file, for whom the April 2015 round of local elections across the country loom large. Japan has just officially gone into recession, voters in the regions have not seen the benefits of the quantitative-easing aspect of Abenomics, and their wages are not keeping pace with inflation. When asked if they want to delay the planned tax increase, most voters will yelp 'YES' in response.

There is self-interest at play also. Abe is scheduled to face his own party in September 2015 in the election for the presidency of the ruling LDP. With an electoral slump in April, Abe could easily be blamed for diminishing the LDP's fortunes through the failure of Abenomics, the policy that bears his name. Abe could be tossed out as prime minister if he is not returned to the presidency of the party.

From this perspective then, the December election starts to look like a self-serving attempt to provide a democratic sheen to what is essentially a spot of internal party trouble.

We can also see that, by interrupting the electoral cycle, the LDP will avoid confronting a hostile electorate in both houses of parliament in the same year (2016), thus limiting the fallout should the economy remain flat.

Cynics will point to the fact that the LDP under Abe is clever to time this election for December, because it is difficult to recall a time when the opposition parties have been in greater disarray than they are at present. But this where the spectre of political risk enters the picture.

With several small opposition parties locked in self-defeating hostilities against each other, the LDP is literally the only political force capable of winning power in its own right. But there is another political entity that needs to be taken into account – the non-aligned voter. The LDP is sitting on only 41% approval ratings; 38% of the country supports no party.

So the real contest in December is not between the LDP and the rest but between the LDP and no-one. Voters can express their democratic dismay at the lack of a viable choice by simply staying away from the polling booth. If less than 50% of the electorate turns out to vote, Abe's resort to the fig leaf of democracy will be exposed.

Moreover, he may lose his precious two-thirds majority in the lower house, now that the electorate is really able to react to the policy agenda that has only been revealed after the last poll in 2012. The post-electoral moves by the Abe cabinet to reinterpret the pacifist clause of the constitution to allow for collective self-defence, and his determination to re-start Japan's nuclear power generators, will now receive the electoral scrutiny they deserve.

Abe wants to claim a mandate for Abenomics before economic policy failures become too entrenched by asking voters to answer an easy question: do you want to delay a tax increase? But voters may flex their democratic muscles in quite another way, slicing the LDP's majority and undermining the very notion of a mandate, by staying at home on election day. This is the political risk Abe has chosen to face off against in December. And it is a huge risk, given that this is an election Japan simply did not have to have.