A Labour leadership challenge would mean Britain could have a seventh prime minister in a decade. Each change of leadership promises renewal, but each delivers fresh disappointment. Meanwhile the problems compound: crumbling infrastructure, polluted waterways, a cost-of-living crisis, a planet warming faster than our policy responses. Why can't a mature democracy fix things it can clearly see are broken?

In the late 1960s, Stanford psychologist Walter Mischel devised a deceptively simple test of human nature. A child is left alone with a single marshmallow and a choice: eat it now, or wait fifteen minutes and receive two. It measures willpower, impulse control, and the capacity to sacrifice immediate satisfaction for a better long-term outcome. Mischel's follow-up studies found that children who waited tended to grow into healthier, better-educated, more emotionally stable adults. But subsequent researchers identified a crucial caveat: children from unstable backgrounds, used to broken promises, were entirely rational to eat immediately, since they didn't trust that the second marshmallow would ever arrive.

Britain, it could be argued, is living through its own national marshmallow test, and the results are troubling. Critics of the current political settlement point out that politicians face structural incentives to fix today's headlines rather than next decade's crises. The five-year electoral horizon means anything beyond it risks being kicked down the road: HS2, the infected blood scandal, Net Zero. Voters, burned by serial betrayal, rationally demand immediate relief on bills, welfare and petrol prices, even when the long-term cost is severe. And hovering over the whole system is the media. Twenty-four hour news demands a fresh scoop every hour, and social media algorithms reward outrage over reflection. If politicians are punished for nuance and rewarded for noise, and voters are algorithmically nudged towards the most inflammatory version of every story, is the entire information environment now rigged against long-term thinking?

If voters rationally distrust politicians, and politicians rationally pander to voters, who bears the moral responsibility for our collective short-termism? And crucially, who bears the responsibility for breaking the cycle? Is it about radical institutional or electoral reform? Does it require a more uncomfortable kind of leadership: politicians willing to tell hard truths, and voters willing to reward them? Who should bear the brunt of any short-term pain? Can we demand courage from leaders we've trained to be cowards? And if so, how do we first rebuild the trust – and the information environment – that makes waiting for the second marshmallow feel rational again?

Chair: Michael Buerk Panel: Mona Siddiqui, Tim Stanley, Ash Sarkar and James Orr Witnesses: Paul Dolan, James Williams, Sonia Purnell and Karl Pike Producer: Dan Tierney Assistant producer: Peter Everett Editor: Tim Pemberton