Descartes’ big problem
How do I know I’m not in the middle of some awful, 101 Philosophy Problems, nightmare? A nightmare of unusual proportions, certainly, that goes on and on with remarkable consistency and detail—but a miasma none the less, completely detached from reality? How do I know I haven’t fallen into the clutches of a malignant demon, intent on deceiving me?
Or perhaps even a malignant doctor? One who has recovered my brain after some nasty accident (involving too many chip butties and driving no doubt) and is now keeping it suspended in a vat of chemicals as part of a ghastly medical experiment. Feeding it made-up ‘sense-data’ along coloured wires: purple for hearing, black for touch, yellow for taste, blue for vision…?