ABSTRACT
David Hume at once finds two relations: causes and effects are contiguous in space and time, and the cause is always prior in time to the effect. The substantial identity of things may be compared in direct perception. But only on the assumption that the causes of a thing’s existence remain unaltered may the continued existence of a thing beyond perception be inferred. Again, although times and places as such admit of comparison without inference, any constancy or variation in relations may be inferred to exist only as a result of causation. That relation, therefore, is the principle of all inferences about matters of fact. In his analysis of personal identity Hume relies on his first principle. The substance in question being something “simple and continued,” its idea would be derived from an impression which remained invariable throughout the course of lives; and plainly no such impression is to be found.
