Should it be a crime to hate women? This unfortunate question is thrown up by the news that misogyny might soon become a hate crime across England and Wales. Two months ago, Nottingham Police launched a trial ‘crackdown on sexism’, investigating cases of, among other things, ‘verbal harassment’ and ‘unwanted advances’ towards women. Now top coppers from across the country are looking into criminalising misogyny elsewhere.

I find this terrifying. Misogyny is vile and ridiculous and I feel privileged to live in an era when, in the West at least, it is in steep decline; an era in which women work, run things, outdo lads at school, and no one bats an eyelid (except men’s rights activists who physically live in their mum’s basements and mentally live in the 1950s). But I am as opposed to the criminalisation of misogyny as I am delighted by its decline. For the simple reason that the state has no business policing people’s thoughts, even their dark thoughts. Have we forgotten this basic principle of the free society?

Imagine the potential for miscarriages of justice in this Orwellian experiment which would investigate people for what they feel (in this case, alleged contempt for women) alongside what they do. Short of inventing a machine that can measure wicked thinking, how does one prove that an individual’s mind is a murky swirl of anti-woman hatefulness? How do we know that the man who engages in an ‘unwanted advance’ towards a woman is driven by ‘ingrained prejudice against women’? He might simply be motivated by attraction to one woman, not hatred for all.

There’s a real possibility that making presumed misogyny a crime will destroy street life as we know it. Sure, there’s nothing big or clever about a bloke shouting ‘Phwoar’ at a woman. But such behaviour — alongside far nicer forms of flirting on the streets and public transport — is a part of public life, and as likely to make people feel happy as it is to make them feel nervous. When the Nottingham Police say that want to crack down on ‘uninvited verbal contact’ — a chat-up line? A come-on? A sexy compliment? — they’re sticking their snouts into everyday conversation, into social life, into utterly non-criminal forms of human engagement.

The extent to which the criminalisation of misogyny invites the state to police everyday interaction is clear from this line in Saturday’s Guardian report: ‘The new classification means women can report incidents that might not be considered a crime and the police will investigate.’ Read that again. Let it sink in. The police might investigate men who haven’t committed any kind of offence — hit someone, harassed someone, damaged property — but whose behaviour has been judged by someone to be misogynistic. The police are now investigating non-crimes. Like bad speech? The wrong demeanour? They could investigate anything which, in Nottingham Police’s words, ‘includes behaviour targeted towards a woman… simply because they are a woman’.

Under our noses, the remit of the police has expanded to include investigating people in essence for their attitudes. Could Dermot Murnaghan be investigated? After all, Emily Thornberry seems to think his line of questioning on Sky News was sexist - or ‘behaviour targeted towards a woman… simply because they are a woman’. Is that hatred? Discriminatory behaviour? What about ‘man-spreaders’, whose agape legs mean a woman cannot sit down on the Tube? Or wolf-whistlers? It sounds absurd, right? But once you invite the cops to investigate non-criminal behaviour that is ‘targeted at a woman… because she is a woman’, who’s to say where it will end?

Nottingham Police insist that, so far, only serious incidents of alleged misogyny have been investigated (although this includes cases of ‘verbal harassment’, and I’d be interested to know what kind of speech that includes). It says its misogynists include individuals who caused actual bodily harm or committed public-order offences. But here’s the thing: even in these cases, when an actual crime is committed, there’s still a problem with categorising it as misogynistic and possibly punishing it more harshly, as often happens with hate crimes.

The problem is that this still amounts to punishing people for their moral, or immoral, ideas. If a man causes actual bodily harm to someone, then he should be arrested, tried and, if found guilty, punished. But he should not be given any additional punishment for the possibility that he was driven by misogyny — or Islamophobia, or racism — because then the state is punishing him for his beliefs. Indeed, the whole idea of hate crime allows the state to police the mind, and ideology itself. And that is wrong. Some people consider communism a hateful creed: would it therefore be acceptable to punish an illegal protester more harshly if he were motivated by communist ideas? Some people think neo-liberalism is a destructive outlook: should we investigate individuals whose free-market fundamentalism is considered by some to be contemptuous of the poor? Shouldn’t class hatred be a hate crime? Why not? Perhaps we should arrest politicians who sneer at chavs — hate speech? — or TV producers who make sensational shows ‘targeted at the poor simply because they are poor’ and in the process 'incite hatred' of a section of society.

We are sleep-walking into tyranny, where thought-policing has become an actual thing. We need to get back to liberal basics. If an individual commits a crime, punish him. If he hasn't committed a crime, leave him alone. And in both cases — for criminal and non-criminal alike — leave their ideology, however warped, out of it. The state should never use its power to tell people what to think.