What Wilber recognizes is that a given truth-claim may be valid without being complete, true but only so far as it goes, and this must be seen as part of other and equally important truths. Perhaps the most powerful new tool he brings to bear in A Brief History is his notion that there are four “quadrants” of development. By looking at hundreds of developmental maps that have been created by various thinkers over the years—maps of biological, psychological, cognitive, and spiritual development, to name just a few—it dawned on Wilber that they were often describing very different versions of “truth.” Exterior forms of development, for example, are those that can be measured objectively and empirically. But what Wilber makes clear is that this form of truth will only take you so far. Any comprehensive development, he points out, also includes an interior dimension—one that is subjective and interpretive, and depends on consciousness and introspection. Beyond that, Wilber saw, both interior and exterior development take place not just individually, but in a social or cultural context. Hence the four quadrants.
