Scepticism as a philosophical term is as old as the Greeks but has more recently been advanced by Montaigne, Descartes and Hume. To these, what little we know that seems certain is based on observation and habit as opposed to any logical or scientific necessity. Thus, sceptical views relate directly to epistemology-the theory of knowledge and what we can know-and, in the modern turbulent world, it is grayling's contention that these are issues that...