Neuroscience can’t tell us the way to govern people’s brains

Our brains love shortcuts. Decisions are often made via a subconscious muddling through, due to the brain’s desire to minimise energy use. It is perhaps why we value neat categorisations of someone’s brain state, despite these being flawed.

Take the age at which you become an adult. Around the world, legal adulthood varies from 16 to 21. This difference matters, as we rightly have different expectations for children versus adults. Some call for this tension to be smoothed by asking policy-makers to consider typical brain maturity levels, ascertained via tools like brain imaging, in matters like criminal sentencing or the right to drive. The idea that our brains don’t fully develop until we are 25 is also becoming popular, but – as we discuss in our special on brain changes – this is wrong. Brains mature at different rates and there are myriad ways to measure their development.

This isn’t the only way neuroscience is looked to for informing policy before the science is ready. Take autism, which may come in several distinct types. A recently proposed category of “profound autism” could identify those with the highest needs, by assessing IQ, language skills and care requirements. This could assist in advocating for services for people in this group, but may exclude those who don’t meet strict criteria. It could also lump together people with speech difficulties with people with cognitive impairments – different neurological profiles demanding different help.

Attempts to use psychological profiling in courts, too, are worrying. When presented as a mitigating factor in some cases, psychopathy has confused matters, taking a slam-dunk prosecution down a messier road. But treating the condition as scientific fact rather than as an evolving framework is dangerous. Recent research shows that, while potentially legally relevant, it can’t be used with confidence.

Our wish to put brains into tidy boxes is natural, and a future in which neuroscience can help us put a fine point on someone’s cognitive state could well be possible. That future, though, is not yet here.