A good overview of Habermas, and some post-critical philosophy.  (Philosophy after the "death of objectivity".)

This is especially important, as Haberman is addressing from his framework, what Wilber is attempting to address with Integral Spirituality.   By the way, here is a review.

Namely, as is said by the article, a “contextualist challenge to the realist intuition".

More than any other work, Integral Spirituality attempts to point out a way how RELIGIOUS TRADITIONS can "transcend and include" the lessons of post-modernism, without losing the essence of the traditions.  That is a big push for Wilber, in the sense of categorizing the types of knowledge domains (inner, outer, 1st person, 2nd person, 3rd person.)