When, exactly, is it OK to talk about gender? Obviously we talk gender all the time, speaking in its tongue, following its script; but when are we allowed to talk about it? A friend decided to tackle a Waterstones manager recently about the fact that every single colouring book in the shop was a gendered one: My First Feminine Mystique Colouring Book for Girls, The Boys’ Colouring Book for Self-Determining Humans, that sort of thing, identify the side you belong to and stay inside the lines.

Don’t you think you’ve got a responsibility to offer more than this to children, asked my friend. Not at all, countered the manager: this is just how boys and girls are. And it ended with the manager accusing my friend of being “on a crusade to change basic biology” – as if a preference for pictures of princesses or cars were a secondary sexual characteristic, like hair distribution or vocal range.

Of course, this is nonsense: children do not just happen to grow up conforming to the social expectations that go with the kind of body they have. They are taught, insistently, with a mix of cajoling, denial, example and punishment that can be more or less explicit but is always ongoing. (In Delusions of Gender, Cordelia Fine describes the efforts of two married researchers to bring up their children without gender stereotypes: even finding a bedtime story became a nightmare of Tippex and careful corrections.)

Any system so embedded must serve a purpose, and there’s a clear hierarchy: man over woman, boy over girl. This isn’t a valuation error whereby femininity has been inadvertently priced lower than masculinity, and we can’t rectify it with a market adjustment that declares “man” and “woman” equal but distinct categories: it’s how gender is supposed to work, a patriarchal innovation that trains boys in activity and girls in passivity to keep the breeding stock in line.

It’s a pro-choice truism that abortion would never be controversial if men got pregnant. This is snappy but sadly nonsensical, because it’s not prejudice against women that makes our reproductive rights so fraught – it’s our femaleness, and a male desire to secure paternity and property against female bodies. Patriarchal gender norms are no more natural or inevitable that motorway networks or out-of-town shopping centres. We’ve invented this system, and we can invent another; but in order to change anything, we have to acknowledge the need to change by seeing ourselves as we are. And increasingly, the language that would let us do that is being silenced.

When the Child Commissioner’s report into “child on child abuse” was published last year, there was much justified distress at the acts of sexual violence and coercion described. But as Sian Norris points out, what this summary of the report didn’t tell readers was that the children being assaulted are overwhelmingly girls, and the children doing the assaulting are even more overwhelmingly boys. The same goes for murder: Karen Ingala Smith has been campaigning since the beginning of 2012 for the killings of women by men to be recorded in official Home Office statistics.

Currently, the Home Office records and publishes data on the sex of victims of homicide and their relationship to their killer. What it doesn’t do is publish information on the sex of the murderers – and this conceals the fact that the people who kill women are overwhelmingly men. We know, with a kind of dull acceptance of horror, that two women a week are killed by their partner or ex-partner, but what we don’t identify is the way that masculine contempt for women and desire to control women is practised with fatal results.

In the same way that the pretence of “not seeing race” allows racism to flourish unexamined, a refusal to acknowledge gender creates a warm pocket in which misogyny can multiply. The leaked Amnesty consultation document on prostitution is a good example of this. This document is explicitly designed to avoid any discussion of gendered power – the introduction informs the reader that the term “sex worker” has been chosen and is “intended to be gender neutral”. But the sex industry is not gender neutral: those who are hired for sex are overwhelmingly women, those doing the hiring are even more overwhelmingly men, and this in a world where (according to the World Bank) women own just 1% of all wealth. [Update 10 February 2014: see this comment for better quality measures of women’s access to capital and power.]

Amnesty may counter that this is an attempt to establish a universal principle rather than a gendered analysis, but what good is a universal principle when the difference of sex is at the very centre of the transaction? The material fact of the body and the social fact of gender both persist, however much one would like to cleanse them from the analysis. And some people would like to cleanse them very much. Disastrously, there are even efforts to purge gender from the language of reproductive rights under the guise of making services more accessible to trans people.

The US organisations Planned Parenthood and NARAL and the UK campaign Education for Choice have all recently given support to a petition calling on reproductive rights organisations to be “pro-trans pro-choice”. But there are few specifics on what a pro-trans pro-choice position would look like in practice, and where one has been attempted, the results create a vertiginous disconnect between the politics of reproduction and the bodies these operate on.

For example, the New York Abortion Access Fund’s values statement, now meticulously drafted to include people of all genders who may need the Fund’s support, opens with a strikingly clumsy piece of phrasing: “The New York Abortion Access Fund believes that every person should be able to determine their own reproductive destiny…” The unintended implications of this formulation are frankly dangerous to abortion rights.

Curtly, every “person” does not have the right to control their reproductive destiny: the men who impregnate women, for example, do not get to be the ultimate arbiters of whether that pregnancy is carried to term. And so one of the key insights of feminism is lost in a swamp of good intentions.

One might think that strictly biological language could offer an escape from such ambiguities, but apparently not: a Texas fundraiser called A Night of a Thousand Vaginas was criticised for its use of the V word by some trans activists, who claimed that it was alienating to trans men. Yet simultaneously in the UK, anti-FGM campaigner Nimko Ali receives vicious abuse accusing her of propagating a “cunt-obsessed culture” because of her work protecting girls from genital mutilation. A woman who claims the right to name and control her female body is still an insurrectionist, and our rebellion is not so advanced that we can afford to surrender any gains.

For those whose sex is misaligned with their sense of their own gender, I have sympathy and sisterhood. Trans women are no threat to feminism, they suffer the sexism that hurts every woman, and they have their share in this fight. But to fight sexism, we must understand that gender is a system of policing female bodies: transgender individuals bravely defy patriarchy’s absurd limitations (and often at the personal cost of horrendous stigma), but they cannot undo patriarchy simply by the force of their own exceptionalism.

We need to talk about what “man” and “woman” mean, and scrutinise the imperfect but profound association between those categories and the male and female humans they respectively act on. Feminism can never be gender neutral, because it is the corrective to a world with a manifest gender bias – albeit a bias that we would rather not acknowledge, even when women are killed by men, even when girls are raped by boys, even when women trade access to their bodies for money while men have the disposable income to pay for an orgasm. We need to talk about gender.