Full Idea
Sometimes it is said that if one has an appropriately coherent system, an alternative system can be produced simply be negating all of the components of the first system. This would only be so if coherence amounted simply to consistency.
Gist of Idea
The objection that a negated system is equally coherent assume that coherence is consistency
Source
Laurence Bonjour (The Structure of Empirical Knowledge [1985], 5.5)
Book Reference
Bonjour,Laurence: 'The Structure of Empirical Knowledge' [Harvard 1985], p.107
A Reaction
I associate Russell with this original objection to coherentism. I formerly took this to be a serious problem, and am now relieved to see that it clearly isn't.