ABSTRACT
This chapter is concerned with Hume’s “proper” arguments for external world scepticism. The proper arguments do not attack the grounds for the belief in body. They present counterevidence. They can be understood in one of three ways: as refutations, as “proof against proof,” or as failed attempts. This chapter argues that they are best understood in the second way. Hume’s proper sceptical arguments conclude that what he called “sensible qualities” only exist on the sensory fields of sentient creatures and that shape, motion, and solidity are inconceivable except as properties of sensible qualities. External world scepticism follows from the fact that external objects are only ever conceived as extended, solid, sensible qualities. The argument for these conclusions constitutes proof against proof because it is based on evidence from eye crossing and distancing that is counterbalanced by evidence from rotary motion and the removal of occlusions. Due to the rareness and difficulty of attending to the results of the sceptical experiments, and the reasoning required to draw inferences from them, the doubt they induce is eventually overcome by renewed experience, but they can have a lasting effect on our cognitive disposition.
