These days, it comes as a surprise to learn that the deep issue about truth which puzzled philosophers from Plato until the seventeenth century was not whether truth could be attained, but how false speech is possible. Thereafter, the issue was reversed. Although certain themes derived from Plato and Aristotle persisted, the intellectual framework within which these themes were explored radically altered. One result is that, in modern times, the dominant worry has been whether it is ever possible to attain truth. Of course, this worry is hardly raised by such mundane questions as whether it is possible to ascertain that a cat is on a mat, or that some cooking pot is black. But over the past three centuries, a major philosophical problem has been how to combat scepticism.