In an intriguing study about to be published, the Dutch political philosopher Ingrid Robeyns poses a question that very rarely gets asked in mainstream politics. When it comes to the personal income and assets of the super-rich, how much is too much? The answer, she suggests in Limitarianism: The Case Against Extreme Wealth, should be anything above €10m. At that point, taxation should intervene, redeploying the surplus for the common good.

Ms Robeyns is not naive. She thinks of her €10m figure as a guiding ideal to be striven for, but one that is unlikely ever to become a reality given the current way of the world. Quite. Nevertheless, her provocative intervention is valuable, because it draws attention to a curious disjunction: as the wealthy have got steadily richer in recent times, soaking up the benefits of free capital movement, share price surges and rising asset values, political talk […]