Participatory Spirituality for the 21st Century
The term "causal" (karana) can be traced back to the Book One of the Gaudapada Karika. Here are the pertinent verses:
11 Visva and Taijasa are conditioned by cause and effect. Prajna is conditioned by cause alone. Neither cause nor effect exists in Turiya.
12 Prajna does not know anything of self or non-self, of truth or untruth. But Turiya is ever existent and all-seeing.
13 Non-cognition of duality is common to both Prajna and Turiya. But Prajna is associated with sleep in the form of cause and this sleep does not exist in Turiya.
14 The first two, Visva and Taijasa, are associated with dreaming and sleep respectively; Prajna, with Sleep bereft of dreams. Knowers of Brahman see neither sleep nor dreams in Turiya.
15 Dreaming is the wrong cognition and sleep the non-cognition, of Reality. When the erroneous knowledge in these two is destroyed, Turiya is realized.
In his commentary, Shankara says that the third state is called "causal" because it is the "seed" (bija) of the other two states. What this means is that the "seeds" of thought (memory, inclinations, etc.) remain in deep sleep and then present themselves when we emerge from deep sleep. What the tradition is doing here is attempting to give a theory for the continuity of consciousness, that is, an account for how it is that the same consciousness (vijnana) reappears after seemingly disappearing for a time (as in sleep, trance, or fainting). Along these lines, the "causal body" is presented as a kind of repository for these "seeds" (= vasana; samskara) of mental states. The alaya-vijnana or "storehouse consciousness," is posited in Mahayana thought for exactly the same reason: it is the repository (alaya) for the vasanas. (There is no "experience" of the alaya-vijnana. It is a metaphysical postulate). Note that Shankara is not saying that "causal formlessness" is the cause of the world, etc. Note also that the Gaudapada Karika explictly says that turiya is beyond cause and effect.
So much for "causal." What do we mean by "formlessness," anyway? It would appear that Wilber has conflated two different applications of the English term "formlessness." Here's how: First, he takes the Buddhist term "arupa," as it applies to the formless attainments (samapatti) in Buddhism, and he associates it with the state of "deep sleep," found in Vedanta. This much is fine, since the two can indeed be seen as analogs, referring, as they do, to a kind of "third" worldly domain in their respective contexts. Both are also similar insofar as they both refer to states bereft of objects of consciousness. At the same time, however, many standard English translations of Vedanta texts translate the term "nirguna brahman" as the "formless brahman". The problem here is that traditionally, the macrocosmic equivalent of the third state/causal body is, saguna brahman, or brahman with form. So, the formless nirguna brahman cannot be said to be the equivalent of the third state of deep sleep. In his various writings, Wilber also relates both the arupa dhatu, the "formless realm," and the dharmakaya, the truth body of the Buddha. But it is not accurate to relate the two in this manner, since the arupa dhatu still pertains to the domain of samsara, while the dharmakaya does not.
Again, to a significant extent, this mess can be traced back to Wilber's appropriation of Da's cateogories, and his attempt to use Da's discourse alongside traditional terminology. In his works, Da refers to nirguna brahman, and nirvikalpa samadhi, as "causal." Since nirguna brahman is also called the "formless brahman" Wilber begins to use the term "causal formlessness" with reference to nirguna brahman and nirvikalpa samadhi. To repeat my point, at the same time, "formlessness" is also used to refer to the third dhatu or loka of Buddhism, which can be seen as the analog of deep dreamless (formless) sleep. However, deep sleep is not traditionally aligned with nirguna brahman: the former is still within the realm of samsara, still worldly, while the latter is transcendent. It is no accident, then, that Ken avoids the classifications "worldly" (laukika) and "superworldly" (lokottara) in his writings, as they would wreck havoc on his system.