The transgender row isn’t going away. Prime Minister’s Questions this week was dominated by a jibe Rishi Sunak made about Keir Starmer’s stance on gender. The Labour leader then lashed out at Sunak for criticising him on the topic while the mother of murdered trans teenager Brianna Ghey was in the Commons.

It’s clear that both sides in this debate are doubling down: Sir Keir has previously said ‘99.9 per cent of women haven’t got a penis’; while Sunak has said that ‘a man is a man and a woman is a woman’ – that’s just common sense’.

As well as a Spectator writer, I am a science teacher. The history of science is littered with fallacies dressed up as ‘common sense’ which have sowed confusion and held back progress. In this case, however, I think that Sunak has chanced upon the right answer.

Sir Keir has previously said ‘99.9 per cent of women haven’t got a penis’

This is a brutal debate. While the gender identity lobby continue to shriek that ‘transwomen are women’, facing them are the self-identified defenders of biological reality. Claiming the backing of science, they insist that women are adult human females, while transwomen are nothing of the sort. But what if both sides are missing the point? Maybe there has been no resolution because we have all been asking the wrong question?

For too long, the belligerents in the gender debate have effectively debated what the terms ‘man’ and ‘woman’ ought to mean. Their opinions are poles apart so it’s no wonder they have failed to find any common ground. As a result, fear and mistrust have torn society in two – there is just too much to lose. If ‘man’ and ‘woman’ become gender identities to be claimed by whoever covets them, women’s sex-based rights become meaningless. But if they become hardwired to XX and XY chromosomes then transsexual people – not to mention other individuals with certain intersex conditions – risk becoming total misfits in a society organised by gametes.

Ask a different question, however, and we might start to get somewhere. Whatever we think these words ought to mean, what actually goes through people’s minds when they use the terms ‘man’ and ‘woman’? Those two particular words might not have been around for very long, but the concept of two sexes predates the English language. Actually, our ability to distinguish male and female existed before language itself – we share it with other species. Chimpanzees can do it; even mice can do it. In fact, any species that cannot tell one sex form another is unlikely to contribute much further to evolutionary history.

Nobody tells us how to breathe, or feel hungry, or happy, and nobody tells us how to perceive men and women. Any law or policy that directs us to override that evolved instinct – ‘common sense’, if you prefer – is doomed to failure in the same way that prohibitions on hunger or happiness. Some things just are. Even without the language to describe them, we can still feel them, and we feel them in the same way as other human beings.

George Orwell’s Newspeak might have constrained language, but it would still not touch the raw experience of how we perceive the world. Even when attempts are made to squash our evolved perception of sex, new words will spring up to convey it. Non-binary people, for example, have been inevitably labelled theyfabs and theymabs (i.e., female or male at birth).There are some things that we feel we need to know, and – equally importantly – need to communicate to others.

Our evolved psychology perhaps explains why the Gender Recognition Act (GRA) did not cause significant controversy when it was enacted in 2004, nor in the years that followed. The first group to apply for Gender Recognition Certificates were those who had already completed the process of gender reassignment, and the GRA brought the law in line with perception. Not everything that looks like a duck and quacks like a duck is necessarily a duck – but if human minds are hardwired to perceive it as a duck, we will have a hard time not calling it one.

The furious reaction against transsexual people was all too predictable

But when Stonewall and like-minded campaigners told us that men who self-identified as women were women, despite what our senses might tell us, society objected. It’s not hard to understand why. A meaningful transition might not change our sex – that really is impossible – but it doesn’t need to change our sex to alter the way others naturally perceive us. Neither warring side will like this but transition can – and needs – to mean something; self-identification can never deliver the same result. We have all been failed by the peddlers of self-ID and the governments that they hoodwinked.

The furious reaction against transsexual people was all too predictable, but the solutions proposed by the ‘biology realists’ are also problematic in real life. Demanding that everyone should always be treated as their biological sex is simply unrealistic. Stonewall failed to redefine man and woman in terms of gender identity – certainly in the UK. We now see attempts to redefine the same concepts in terms of chromosomes. But even if those campaigns succeed in changing the law, the victory will be hollow. Because where chromosomes and instinct diverge, instinct will always prevail – as it has done for millions of years, and in species other than our own.

Of course, this argument doesn’t answer the question of whether human beings should be allowed to transition in the first place. (Though it is hard to envisage a UK government imposing rigid and distinct dress codes and hairstyle regulations on each sex, and banning hormone therapy and gender surgery for consenting adults.) Nor does it make any judgment on the legal status of transmen and transwomen. But it does open up a more transparent debate, and it explains why those questions have been so hard to tackle. If transsexuals are perceived to be the other sex then instinct cannot be ignored.

This government is unlikely to last for long, but another one will come after it. It will face many of the same issues. Assuming, as seems likely that Labour win the next election, Starmer and his comrades would be foolish to ignore Sunak’s words. Unwittingly perhaps, he stumbled on that evolved instinct that we have always known but rarely articulated. Attempts by politicians, philosophers and even scientists to redefine man and woman are as futile as attempts to redefine hunger or happiness. That is just common sense!