Full Idea
I think it is wrong to tie down the advocates of the coherence theory to a precise definition. ...It would be altogether unreasonable to demand that the moral ideal should be exhaustively defined, and the same may be true of the ideal of thought.
Gist of Idea
We can no more expect a precise definition of coherence than we can of the moral ideal
Source
A.C. Ewing (Idealism: a critical survey [1934], p.231), quoted by Erik J. Olsson - Against Coherence 7.6
Book Reference
Olsson,Erik J.: 'Against Coherence' [OUP 2008], p.137
A Reaction
I strongly agree. It is not a council of despair. I think the criteria of coherence can be articulated quite well (e.g by Thagard), and the virtues of enquiry can also be quite well specified (e.g. by Zagzebski). Very dissimilar evidence must cohere.
Related Idea
Idea 21497 If undetailed, 'coherence' is just a vague words that covers all possible arguments [Ewing]