When I talk with 17- and 18-year-olds applying to the University of Bath, where I teach, I am often asked whether they should choose to study maths or one of the other A-level subjects they are taking. My answer is almost always the same: they should take maths. This advice is not just a bias of my background, but stems from the fact that mathematics is the language of science. Studying mathematics doesn’t shut any doors. It keeps them open. With a strong mathematical background, it’s relatively easy to transfer to one of the other sciences, economics, or any number of quantitative areas. Mathematics graduates are consistently ranked among the most employable. This seems to be the thinking behind Rishi Sunak’s controversial new target to have all pupils in England study maths until the age of 18. Yet compulsory post-16 mathematics education is perhaps not the best way to encourage more pupils to take the subject. It’s not as if maths is languishing in the doldrums. It is already the most popular A-level subject; many thousands more students take maths than its nearest competitor, psychology. Students are already realising for themselves just how important a good working knowledge of mathematics might be for their prospects. Further strengthening these numbers would surely be better achieved by demonstrating the importance and relevance of maths to our children and the opportunities it can open up, rather than forcing them to endure a subject that many find unenjoyable. This blanket policy runs the very real risk of acting as a perverse incentive, putting pupils off post-16 education in maths altogether. And what of the toll on other subjects? Making one subject mandatory removes students’ capacity for taking others. That reduction in enrolments is likely to fall disproportionately on the humanities, as students seek to take subjects that synergise with each other. The move sends a clear message that the humanities are less valued than the sciences because of their lack of practical application. This is the same battle that we face at the pure end of the spectrum that makes up the subject of mathematics. In pure maths, we pursue knowledge for knowledge’s sake, without a view to its potential future uses. When a young man studying under the Greek mathematician Euclid asked: “What do I gain by learning geometry?” Euclid told his servant to “give him threepence, since he must make a gain out of what he learns” and promptly kicked him out of his academy. Not everything that is studied should be studied simply because it has some clear utility for the economy. Aside from this, is the policy even feasible? Exactly how the prime minister intends to enforce his plan remains unclear. Against the backdrop of a long-term shortage in maths teachers, the government again failed to meet its target for recruitment in 2022 despite significantly reducing that target. Almost half of all secondary schools are already using non-specialist teachers for maths lessons. Despite a £2.3bn increase in core funding promised to schools for five- to 16-year-olds’ education in the autumn statement – offsetting the real-terms cuts of the last decade – no extra funding has been promised to sixth-forms and further education colleges, which would be responsible for shouldering most of the burden of implementing this plan. It’s true that better levels of numeracy in the population would benefit everyone – and not just because of our increasingly data-driven economy. A better understanding of mathematics gives us the power to be sceptical of the statistics in newspaper headlines, the “studies” pushed at us in adverts or the half-truths that come tumbling from the mouths of our politicians. Better numeracy is good for democracy. Even a little improvement in mathematical literacy against the backdrop of our increasingly quantitative society can help us harness the power of numbers for ourselves. Sunak has spoken of his personal motivation for the policy – offering the nation’s pupils the opportunities he was afforded by his own education. But policies must be based on more than just a warm, fuzzy feeling. They must be based on evidence. So far we are yet to see the hard evidence that suggests this policy will be of net benefit, let alone be implementable in practice. If this policy is ever to be actually introduced, we need the prime minister to show his workings-out. Kit Yates is director of the Centre for Mathematical Biology at the University of Bath and author of The Maths of Life and Death