When will the government tell us what kind of free speech it’s going to ban?

We know it's coming, because they keep telling us. They just won't give us any details. The counter-extremism bill will clamp down on non-violent freedom of speech. But exactly what speech and by whom? That is unclear.

David Cameron's speech on extremism today was hyped as the most important he has delivered on the subject. The extracts released in advance were extremely wishy-washy and confused. So was Theresa May's subsequent appearance on the Today programme, in which she was again unable or unwilling to say exactly which kinds of free speech would be outlawed. Education secretary Nicky Morgan had a similar problem in relation to public bodies' new legal responsible to prevent extremism a few weeks back.

The problem is this: If you really ban groups and people 'opposed to British values' – defined apparently by those who want to overthrow democracy – you'll need to ban the Socialist Workers party and Platonist philosophers alongside Islamic extremists.

This difficulty is never mentioned. Instead there is a daily drum-beat of rhetoric, establishing the need to deal with 'non-violent extremism' but never offering any firm details as to what it might entail. They are softening us up. They are making the argument without any of us having the information with which to counter it. Whenever the conversation is moved on to specifics, ministers get themselves in a terrible mess – as Morgan demonstrated when she proposed measures so wide-ranging they would have seen her arrested for extremism herself.

The advance sections of Cameron's speech are an exercise in simplification, muddle and imprecision.

He seems confused that no-one debated whether it was right or wrong that terrorists murder people after the Charlie Hebdo massacre, seemingly without recognising that it's because this is not a controversial point that it was not debated. He thinks that because September 11th took place before the Iraq war it couldn't have had anything to do with foreign policy, even though Osama bin Laden was really quite specific about this issue. It is all tremendously simple-minded, self-serving and unhelpful.

The counter-extremism bill has been promoted for nearly a year in advance

But at the heart of the extracts is the same point the government has been making for just under a year now: that non-violent extremism must be tackled. Here's a key extract. You'll have to forgive the dreadful way these things are written, where full stops take the place of commas and subordinate clauses are presented as sentences. That's the fashion.

"You don't have to support violence to subscribe to certain intolerant ideas which create a climate in which extremists can flourish. Ideas which are hostile to basic liberal values such as democracy, freedom and sexual equality.  Ideas which actively promote discrimination, sectarianism and segregation. Ideas – like those of the despicable far right – which privilege one identity to the detriment of the rights and freedoms of others. And ideas also based on conspiracy that Jews exercise malevolent power or that Western powers, in concert with Israel, are deliberately humiliating Muslims, because they aim to destroy Islam."

None of this stands up. We are not about to outlaw the expression of opposition to sexual equality, unless the men-only Garrick club is going to be closed down alongside the Islamist preachers. Will those who actively promote segregation really be handed down a disruption order? Will the same apply to the students on campus banning white men from political meetings? Will those who "privilege one identity" really be subject to the law, given that surely includes the SNP and Ukip alongside the National Front? And are we really about to clamp down on the weirdos who bang on about Jewish conspiracies and how September 11th was an inside job on Facebook? Surely they are entitled to be as mistaken as they please.

It is simply impossible to really enforce the type of legislation Cameron is arguing for in an even-handed way, unless we turn Britain into a police state where only a narrow centrist political consensus is tolerated. You might guess that the law will specifically only mention Islamic extremism of this sort. That would be morally wrong but also surely vulnerable to legal challenge as an act of religious discrimination embedded into the legal system. How could one justify targeting homophobia if expressed by a Muslim but not when expressed by a Christian? Anyway, ministers have been clear they are keen to target the far-right alongside Islamists.

Education secretary Nicky Morgan considered homophobia extremist, but her own voting record is open to question

We have almost no information. We know only the types of bans which will apply – banning orders for groups, disruption orders for individuals and legal actions of varying strengths for locations. And there is some limited idea of how severe the controls will be. We know for instance that they will almost certainly include police authorisation for social media use and possibly even the individual messages sent. But we do not know who will be targeted, or what for.

In all likelihood the impossibilityof disentangling different kinds of extremism will mean the Home Office is likely to claim that discretion for itself, with the home secretary making ad hoc day-to-day decisions over individuals. This would run against the thrust of the recent report by the government's independent reviewer of anti-terrorism laws, which recommended the home secretary make fewer individual decisions on spying and hand the responsibility over to a judge-led body.

But it also contributes to the sense that the law is not fair and instead singles out those, like Muslims, who are considered politically difficult. And whatever Cameron's views, that sense of grievance – in this case entirely justified – does contribute to the alienation which leads to terrorism.

This softening up has gone on for long enough. The government is using its upper hand to lay the ground for what seems to be an extremely wide-ranging clamp-down on free speech but it does not have the good grace to tell us specifically what it intends to ban. Cameron can make as many speeches as he likes but this isn't a debate – it's one side talking without the other having any information on which to evaluate it.

It's time to put up or shut up and tell us exactly what the government proposals are.