The appropriate choice between business and public enterprise is determined by the interaction between a financial time horizon and the product or project’s economic life. The prevailing interest rate defines a precise credit time horizon which is a temporal outer bound for commercial enterprise. Projects which need longer to break even cannot be funded by business alone. Long-term projects face uncertainty and attempts to control it by means of rigid contracts lead to inferior outcomes. A ‘franchise’ overcomes the temporal boundary. Protection from uncertainty is provided by social and government agencies. Investment ‘manias’ set aside time horizons and can leave a legacy of real assets. Public–private partnerships for infrastructure development are a franchise intended to overcome credit time horizons. They were embraced by New Labour, but have given rise to inefficiency and corruption and are currently in decline. The time-horizon model undermines the standard argument for market superiority. It turns Hayek on his head: it is financial markets that require certainty, whereas social and public agencies manage in its absence.