Full Idea
A single explanation of a fact only explains it from a single point of view.
Gist of Idea
A single explanation must have a single point of view
Source
William James (The Sentiment of Rationality [1882], p.23)
Book Reference
James,William: 'Selected Writings of William James', ed/tr. Bird,Graham [Everyman 1995], p.23
A Reaction
I take this to imply that multiple viewpoints lead us towards objectivity. The single viewpoint of an expert is of much greater value than that of a novice, on the whole.