 Robinson also led the critique of the use of aggregate production functions based on homogeneous capital – the Cambridge capital controversy – winning the argument but not the battle.The writings of Piero Sraffa were a significant influence on the post-Keynesian position in this debate, though Sraffa and his neo-Ricardian followers drew more inspiration from David Ricardo than Keynes.Much of Nicholas Kaldor’s work was based on the ideas of increasing returns to scale, path dependency, and the key differences between the primary and industrial sectors.