Alastair Campbell has claimed that The Sun’s decision to back the Tories in the next General Election is “far from devastating” to Labour.  It is indeed unlikely to be as “devastating” as it was to Neil Kinnock in 1992 or to John Major in 1997. The paper’s circulation has fallen in the last decade (although it remains over three million) as the number of alternative media channels had risen exponentially. The Sun can no longer claim it “won it”, even assuming if it ever did.

Nevertheless, only a fool would say it was not significant. The Sun defined and demonized the loony left in the 1980s. Its coverage of Labour’s 1992 campaign was remorselessly hostile and surely influenced the tightest election of the last 30 years. Tony Blair’s successful wooing of the paper once he came to power not only helped secure his election victories but was also totemic: another nail in the coffin of Old Labour and a sign to the world that his party was mainstream and credible.

Taken at face value there is something extremely ugly in all this. It reeks of elections being decided by a tiny coterie of editorial staff and their proprietors who have only the most superficial accountability to the public; of democracy being bent out of shape by a small number of private interests and personal grudges.

But should we take it at face value? Does The Sun actually matter? How many of its readers will vote differently because of its new editorial line?

This is fiendishly difficult to answer. People steadfastly refuse to admit that they are seriously influenced in their politics by the newspapers they read. No-one likes to appear as a leaf to every editorial wind that blows. More problematically, there is closed circle of opinion that is difficult to crack: people read a newspaper because they agree with it, but they agree with it largely because it agrees with them, supporting and reinforcing their existing opinions. Which drives which?

In theory, a switch like The Sun’s should help us answer that. If its circulation dropped dramatically because of its editorial shift, we would have a good idea of how many people were driven by pre-existing political opinion, rather than by what they read in their daily. The fact that The Sun has been largely hostile to Gordon Brown over the last two years makes this scenario rather unlikely, however. Its editorial change is unlikely to be that noticeable.

Better still, if we had data on the political affiliation and voting intentions of Sun readers yesterday and gathered the same data tomorrow – or more realistically six months ago and in six months time – we might get some idea how the editorial shift affected them; although only some idea: there would be naturally a great deal of ‘noise’ in the data, as a myriad of other factors shape political opinions. (Does anyone know of any such research and if so could they include a link in their post?)

Assuming – and it is an assumption waiting to be proved wrong – that such public backing or booing from a newspaper does impact public opinion, does it matter? Is it only sensitive lefties who get upset by The Sun’s posturing (whilst remaining silent about The Mirror’s anti-Tory agenda) or is there something genuinely sinister in the power that proprietors, editors and journalists wield over their malleable readers? Shouldn’t newspapers inform democracies rather than deform them?

In utopia, yes: we would all be informed and nuanced in our opinions and read news from at least two sources, comparing and contrasting the different perspectives in order to locate the truth about an issue.

But back in the real world most people don’t have the time to triangulate media opinions and, in any case, don’t wish to. We have our opinions and we want to read something that tells us we are right.

If this leaves us more ignorant, polarised or malleable, then so be it. Much as we might like to blame Murdoch for his impact on the political landscape, it is difficult to do so without incurring any charge of hypocrisy.

As long as the media landscape remains relatively open, with monopolies kept at bay, and readers have at least the chance to gather information and opinions from different sources, the current situation is the best we can hope for.

As with politics, the public gets the media it deserves.

Nick Spencer is Director of Studies at Theos.