Three-dimensional external objects are never exhaustively presented in perception — they are always given from a partial point of view, leaving room for revisions.

Ingarden takes Husserl to have been driven to transcendental idealism largely by his epistemological goals and transcendental approach to phenomenology. If the very idea of three-dimensional external objects makes sense, it would be essential that our perceptions of them are inevitably inadequate: They may be presented from one point of view or another, but never exhaustively and entirely -- so room is always left open for new perceptions that would lead us to entirely revise our past judgments.