Labour supporters aren’t supposed to say this, but there are some constituencies in the UK where it makes perfect sense to not to vote Labour if your main interest is in preventing Brexit. Take Richmond Park: in the 2017 general election, the Conservatives beat the Liberal Democrats by just 0.1%, with Labour trailing at 9% of the vote. The wider borough, Richmond upon Thames, which voted remain by a landslide, also went to the Liberal Democrats in the 2018 council elections, as they gained 24 seats. In Richmond Park, voting Liberal Democrat makes sense if you want to remain.

But it makes a lot less sense to vote Lib Dem in Filton & Bradley Stoke, where the party received just 6% of the vote in 2017 compared to Labour, which won 42%. And yet this is what GetVoting.org, the controversial remain tactical voting tool released by Best for Britain this week to howls of disbelief, is advising its users to do. Best for Britain, the organisation that built the tool, has been surprisingly evasive about why GetVoting.org is producing extraordinary recommendations like this one. If your aim is to prevent Brexit, this tactical voting tool deserves some scrutiny.

Best for Britain says it is using a method of predictive analysis called MRP (multilevel regression and post-stratification), some versions of which correctly predicted that Donald Trump would win the 2016 US election. This has conferred a reputation for clairvoyance on the tool, but the reality is not so simple.

Why talk about how you would change the system when you could game the system?

The most celebrated uses of MRP have been in predicting national results on the basis of aggregating projections for every constituency. But in the case of GetVoting.org, the emphasis is on predicting outcomes in individual constituencies. This is not to say that MRP is an inaccurate model – but that it is highly complex and abstract, and should not be represented as if it reflects interviews with large volumes of people in each constituency.

The chief executive of Best for Britain, Naomi Smith, argues that the strength of this MRP model is that it has a sample size of 46,000 – compared to national polls in which the average sample size is around 2,000. But this is misleading: predicting constituency-level results is a different ball game to predicting national ones. As the psephologist Dr Luke Blaxill has pointed out, divided between 650-odd constituencies, a sample size of 46,000 amounts to about 70 voters per constituency.

Indeed, if the Lib Dems really were performing so astonishingly well that they had gone from 6% to 42% in one constituency, you would expect to see a corresponding swing in national polls – which still show them in third.

“Aha,” say the advocates of the tactical voting tool, “you are forgetting the results of the EU elections!” But these elections are notoriously terrible predictors of general elections because the public has not tended to take them that seriously. I’m not sure why the designers of a tactical voting tool for remainers are insisting we pay so much attention to an election in which the Brexit party won by a landslide. Nor why they would release their tool so long before voting day, given that the polls can and will move before then, possibly rendering the recommendations out of date.

Former Lib Dem leader Vince Cable at a Best for Britain event in London on 30 October. Photograph: Andy Rain/EPA

Of course, it is possible that the voting tool will surprise us all and deliver predictions that are fantastically accurate. But the more interesting political question is: why are liberals and centrists so fixated on a tactical voting tool as the means of success?

Whatever you think of the Tories, they are fighting it out with Labour over competing visions for the country. Theirs is nationalist, capitalist and authoritarian. Labour’s is socialist, green and egalitarian. But the Lib Dems and their allies at Best for Britain don’t seem to regard politics as the domain of existential choices about what kind of society we want to be. Instead, they are deploying carefully selected data – to give the appearance of technocratic authority – in order to promise there are no tough choices in this election. All you have to do is follow the data – their data! – and everything will be fine. Why talk about how you would change the system when you could game the system?

The Liberal Democrats have even indulged in outright mischief. Their leader, Jo Swinson, was chastised by the broadcaster Sophy Ridge over the party’s use of a dubious graphic which, at first glance, suggested the Liberal Democrats were the best anti-Tory choice in North East Somerset. Only when one examined the small print did it become obvious that the question participants were asked was: “Imagine that the result in your constituency was expected to be very close between the Conservative and Liberal Democrat candidate, and none of the other parties were competitive. In this scenario, which party would you vote for?”

And yet hoping to win via technicalities and a series of PR stunts is emblematic of the kind of centrism Swinson represents. It is a politics that believes the great ideological debates have been settled, and that all that remains is managerialism and optics. That she is entirely wrong about this has been obscured so far by her canny decision to position the Lib Dems as the party of remain. But sooner or later it will become clear that the Lib Dems’ bollocks to Brexit revival is merely a tarpaulin covering a giant hole where a political vision should be.

• Ellie Mae O’Hagan writes about politics and culture for the Guardian

• This article was amended on 7 November 2019 to clarify a description of the MRP model