In this episode I introduce a brief history of scepticism, that is the doubt whether we can have any certain knowledge of the external world. I start with the Greek philosopher Sextus Empiricus who lived in the second century AD. His arguments were taken up and developed by the French Renaissance writer Michel Montaigne (1533-1592). Two French philosophers - Marin Mersenne (1588-1648) and his friend Pierre Gassendi (1592-1655) - rejected this rather defeatist version of scepticism and proposed a more moderate form: it accepts that we can have knowledge of appearances but know nothing about their underlying causes. Modern scepticism, as represented by the philosopher Karl Popper and the physicist Sean Carroll, defends the idea of conjectural knowledge. Science knows about appearances and the underlying causes but this knowledge is conjectural because it is always at the risk of refutation and revision.

Literature:

• Sextus Empiricus, Outlines of Pyrrhonism
• R. H. Popkin, The History of Scepticism (3rd edition 2003)
• N. A. Pinillos, Why We Doubt (OUP 2023)
• F. Weinert, Karl Popper - Professional Philosopher and Public Intellectual (Springer 2022).