Full Idea
What distinguishes a coherence theory of justification is simply the claim that nothing can count as a reason for holding a belief except another belief.
Gist of Idea
Coherent justification says only beliefs can be reasons for holding other beliefs
Source
Donald Davidson (Coherence Theory of Truth and Knowledge [1983], p.156)
Book Reference
'Epistemology - An Anthology', ed/tr. Sosa,E. /Kim,J. [Blackwell 2000], p.156
A Reaction
I think I agree fully with this. Red patches and headaches I count as evidence rather than as reasons. Since a red patch can be hallucinatory, and a headache can be dreamed, they can't possibly embody true propositions without critical evaluation.