Full Idea
All empirical evidence is of particular truths. Hence, if there is any knowledge of general truths at all, there must be some knowledge of general truths which is independent of empirical evidence.
Gist of Idea
Empirical truths are particular, so general truths need an a priori input of generality
Source
Bertrand Russell (Our Knowledge of the External World [1914], 2)
Book Reference
Russell,Bertrand: 'Our Knowledge of the External World' [Routledge 1993], p.65
A Reaction
Humean empiricists respond by being a sceptical of general truths. At this stage of his career Russell looks like a thoroughgoing rationalist, and he believes in the reality of universals, relations and propositions. He became more empirical later.