Full Idea
The relation between a sensation and a belief cannot be logical, since sensations are not beliefs or propositional attitudes. The relation must be causal. Sensations cause some beliefs, but they do not show why the belief is justified.
Gist of Idea
Sensations lack the content to be logical; they cause beliefs, but they cannot justify them
Source
Donald Davidson (Coherence Theory of Truth and Knowledge [1983], p.157)
Book Reference
'Epistemology - An Anthology', ed/tr. Sosa,E. /Kim,J. [Blackwell 2000], p.157
A Reaction
This is, I am beginning to think, the single most important idea in the whole of modern epistemology. Animals have beliefs caused in this way, and because they only have simple beliefs about immediate things, most of their beliefs are true.