Descartes, the father of modern philosophy, in his pivotal workDiscourse on method, published in 1637, set himself the task of doubting everything. From that starting point, he then tried to find a solid base of certainty. Over the years, epidemiologists have attempted to follow the Cartesian approach, not least those epidemiologists who are interested in that heterogeneous group of conditions called the “cerebral palsies”. To doubt everything requires imagination and …