Full Idea
Traditional empiricism takes impressions, ideas or sense data as the basic unit of empirical thought, but Quine takes account of the theoretical as well as the observational; the unit of empirical significance is whole systems of belief.
Gist of Idea
Quine's empiricism is based on whole theoretical systems, not on single mental events
Source
report of Willard Quine (works [1961]) by Alex Orenstein - W.V. Quine Ch.1
Book Reference
Orenstein,Alex: 'W.V. Quine' [Princeton 2002], p.1
A Reaction
This invites either the question of what components make up the whole systems, or (alternatively) what sort of mental events decide to accept a system as a whole. Should Quine revert either to traditional empiricism, or to rationalism?