We saw how Descartes used a form of extreme scepticism: he doubted everything he thougt he ‘knew’, even the evidence of his senses.

He gives examples of three different ways in which he may be wrong about how he perceives the world. Firstly he uses the argument from illusion; (the stick in the water) to show that his senses are not reliable. Secondly he suggests he could be dreaming: the argument from dreaming. And thirdly he considers that a malignant demon may be deceiving him deliberately about everything: the argument from deception

We also learned the meaning of ‘epistemology’, it is the study of what it is possible to know: is knowledge of the world possible, if so what?