The Kaldor/Knight controversy: Is capital a distinct and quantifiable factor of production?

Controversy focuses on three questions: Is capital a distinct factor of production? Is capital quantifiable in a theoretically consistent manner? Are process stories necessary around convergence to, or changes in, equilibrium interest rates? To all, Kaldor answers 'yes' to Knight's 'no'. The controversy is historically important in: 1) shifting issues in recurring twentieth century capital theory controversies from periods of production to production functions, from roundaboutness to diminishing returns; 2) revealing Knight's position on increasing knowledge offsetting diminishing returns over time as an unacknowledged 'precursor' of new growth theory; 3) marking the turning point for Kaldor's attachment to Austrian theory.