Starting with Richard Popkin's essay of 1963, 'Scepticism in the Enlightenment', a new investigation into philosophical scepticism of the period was launched. The late Giorgio Tonelli and the late Ezequiel de Olaso examined in great detail the kinds of scepticism developed during the Enlightenment, and the kind of answer to scepticism that was developed by Leibniz. Their original researches and interpretations are of great value and importance. As...