Scepticism as a kind of philosophy

Scepticism has been one of the standard problems of epistemology in modern times. It takes various forms – the most general one being the thesis that knowledge is impossible; but equally prominent are such versions as the notorious doubt about the existence of an external world, inaugurated by Descartes'Meditations, or doubts about the existence of objective values. Philosophers who undertake to refute scepticism – still a very popular exercise – try to show that knowledge is possible after all, or to prove the existence of an external world, and so on. Sceptics, generally speaking, are seen as radical doubters – philosophers who call into question assumptions that are usually taken for granted by ordinary people as well as by other philosophers. Those doubts have to be refuted by showing that they are in some way unjustified.