Liberal Left's opposition to the Liberal Democrats' involvement in the coalition, as set out by here Linda Jack, is based on a number of questionable premises and an unwillingness to consider the realistic alternatives.
The group's vice-chair, Richard Grayson, criticises what he sees as the party's change of view on the deficit. He is wrong. Pre-election, Vince Cable's key message on the deficit was that a judgement on the timing of austerity had to be based on economics rather than politics or ideology. On that basis, in the run up to the election, the party adopted the working assumption that cuts would start in earnest in 2011-12, with some savings made immediately as a "down payment".
Yet by the time of the coalition negotiations the economic situation had changed. Alistair Darling was attending emergency meetings in Brussels as the threat of contagion loomed large over Europe. With one of Europe's biggest budget deficits, Britain was in a perilous position. And it's for this reason that the party's judgement changed. And in my view we've been proved right - yes, the economy might be growing more slowly than we would like, but the deficit is coming down and we avoided being caught in the centre of the fiscal crisis that spread through Europe.
And there is a more compelling reason why Liberal Left are wrong to oppose our involvement in the coalition: the alternatives would have been much, much worse.
A coalition with Labour and a number of the smaller parties in Parliament was never a serious proposition, both because of the numerical difficulties and because of Labour's intransigence. In hindsight it's clear that most in the Labour party weren't interested in joining a coalition. They'd rather be in opposition.
A confidence and supply arrangement was another option, but in my view those who think this would have been better for either the country or the Lib Dems are mistaken; it would have all the downsides of coalition with few of the benefits.
That left only a coalition or a minority Tory administration. Within weeks of forming a minority government, George Osborne would have produced the most populist, tax-cutting budget imaginable and, when it failed to get through the Commons, David Cameron would have visited Her Majesty, Parliament would have been dissolved and a new general election - probably in autumn 2010 - would have ensued. And at this point, both Labour and the Tories would have had one message: "it's time for you to vote for one of us - the Lib Dems have rejected the option of power". The Lib Dems would have been squeezed like never before; every marginal - virtually every Lib Dem seat - would be vulnerable. We'd have been reduced to a miniscule Parliamentary Party.
And the Tories would have got their majority. Even the most anti-coalition of Lib Dems can't seriously say that that would have been a preferable option.
The combination of being in government and being members of a truly democratic party leaves Lib Dem members with an immense amount of influence. We should use it as best we can to make this government is fair and as liberal as possible - not blindly supporting but constructively engaging, working with Lib Dem ministers, who we know to be honest, caring liberals, to achieve as much as possible.
We won't always get our own way, as we shouldn't as a party that received 22 per cent of the vote and fewer than one in ten seats in the Commons at the last election. But we are punching above our weight to implement hundreds of long-standing party policies.
Going into coalition was the best option for the Liberal Democrats and for the country, and the arguments why remain just as compelling today as they did on 11 May 2010. Party members must concentrate on making it work, for the country and for the party. Opposing from the sidelines is no solution at all.
Nick Thornsby is a Liberal Democrat member and activist. His own blog can be found here