Theresa May has just announced her plans for Brexit and they are crystal-clear. At the heart of her proposal is membership of the single market – and the long sought after reassurance that jobs, particularly in the north of England, will be safe. There’s good news for EU nationals, who can continue to live and work here, and free movement for workers will continue in the future too – meaning our economy will be better off and our communities enriched.

Environmental rules and workers’ rights are safe – the prime minister’s decision to remain a part of the biggest trading area in the world will safeguard those protections. We’re set to leave the EU, as the British people voted for by a small majority, but the government has a plan to retain and enhance the many benefits of EU membership, and an interim arrangement with the EU is in place in case the negotiations don’t get done in the two years allowed. May’s promise of “Brexit meaning Brexit” remains true but, at long last, she’s given MPs the details we need to make an informed choice about our vote on triggering article 50.

Sounds like a dream, doesn’t it? That’s because it is.

The reality of the situation couldn’t be more different. Five months after the referendum, and with a supreme court appeal on article 50 looming, we’re still left with little more than hot air from a government that is driving us towards the Brexit cliff edge, with the doors of the car locked and its eyes firmly shut.

What will Brexit mean for the EU nationals who live and work in our neighbourhoods? Will our beaches and wildlife still be protected? What kind of trade agreement will we have with Europe? Ministers just keep shrugging their shoulders, demanding our trust when they’ve done nothing discernible to earn it.

It’s extraordinary they expect MPs to simply fall in line without knowing what we’re voting for

Though I’m proud to have fought as hard as I could to stop Britain from leaving the EU, I’m not one of the MPs who immediately pledged to vote against article 50 after the high court’s ruling on the issue earlier this month. In the heat of the moment it would have been easy to offer an immediate kneejerk refusal to trigger article 50 in any circumstance. Similarly rash is the response of those, like the Labour leadership, who have gone too far other way – making an early promise to support the government in beginning the Brexit process. By doing so they’ve given away any bargaining power they had – and given the government’s agenda a real boost.

Instead, I’ve come to a considered conclusion, given the circumstances and based on both principle and logic: I won’t be voting to trigger article 50. Without any plans to properly involve parliament before a vote, to call a general election or offer the protection of a referendum on the terms of any deal, how could I – as a democrat and someone who believes in social and environmental justice – possibly vote to throw the country into the potential nightmare of leaving the EU within two years without any proper plan? I don’t know whether it’s primarily arrogance or incompetence that’s causing such anti-democratic posturing by the Conservatives, but I do know it’s extraordinary they expect MPs to simply fall in line without knowing what we’re voting for.

Ultimately, voting to trigger article 50 – without any firm guarantees about what Brexit would mean, for everything from the security and family life of the many EU nationals working in places such as Brighton’s universities to whether there’s any way to enforce standards for the quality of the air we all breathe – would risk undermining the work that the constituents of Brighton Pavilion put me in parliament to do, and the pledges my party made to the more than 1 million people who voted for us.

The government seems to have morphed a marginal vote in favour of leaving the EU into a phantom majority that wants us out of the single market – and all of the benefits it entails – despite the public never being asked their opinion on it. Without any solid proposals for an interim deal after two years of negotiation, the Conservatives’ plan is particularly reckless.

I still believe that Britain is better off as part of the European Union, and I’ll be campaigning in the next election for our continued membership of the biggest peace project in history. As a constituency MP and co-leader of a national party, I believe that I have a duty both to represent my constituents and to act in the country’s interest – and I firmly believe that voting to trigger article 50, with things as they currently stand, runs counter to both of those roles.

Our country has been shaken to the core by the EU referendum campaign and the divisions it revealed – and what happens next will define us for generations to come. That’s why I’m more committed than ever to both exposing and opposing government recklessness on Brexit, and looking to build a more united, fairer and more democratic Britain – whatever the outcome of negotiations with Europe.