As it happens I reviewed this book—The Innate Capacity: Mysticism, Psychology, and Philosophy (Oxford, 1998)—shortly after it came out. I think you’re right that the idea of “pure consciousness” is an important one when it comes to combating constructivists like Steven Katz, though looking back at my notes I’m not so sure the editor of the volume, Robert K. C. Forman, is speaking about quite the same thing as the Platonists are when they refer to the Nous or “pure Intellect”. In case you’re interested, here are a few words from my review:

The Innate Capacity is a sequel to its editor’s earlier collection The Problem of Pure Consciousness, and like the former book it concentrates on what the contributors call a ‘post-constructivist approach’ to religious experience. In the view of constructivists like Steven Katz, all experience is to be understood on the model of sense perception and is thought to be determined not simply by perceptual givens but by the language and culture of the perceiving subject. It follows for such interpreters that even the allegedly trans-empirical experiences of the mystics are, in fact, built up from the materials afforded by their varying religious and conceptual backgrounds.

Forman and others argue by contrast that there exists at least one kind of mystical state, a ‘pure consciousness event’, in which the human subject enters into a wakeful but object-less mode of cognition. All preconditions, assumptions, and intentional objects are extinguished, and the knower becomes aware of nothing but the knowing itself. All of us, it is argued, have an ‘innate capacity’ for this experience, and it is therefore not surprising that descriptions of such a state are to be found in all religions, nor that by its very nature it should elude the descriptive and explanatory powers of the empiricists and constructivists.

Forman clearly and forcefully defines the territory, calling the bluff on all those reductionists who have presumed to dictate the limits of consciousness. When it comes to what can and cannot be known, ‘the statements of philosophers have no legislative force. No matter how many Humes, Moores, or Hamiltons observe that they cannot catch themselves devoid of [sensory] perceptions, this tells us little about what a Hindu monk, Dominican friar, or Sufic adept might experience after years of yoga, Jesus Prayer, or Sufi dancing” (16).

The remarkable similarities in the accounts of such experiences lead Forman to posit a ‘perennial psychology’ (27ff). Unfortunately, in his efforts to distinguish this psychology from a perennial philosophy, the editor makes the common mistake of suggesting that the latter is based simply on a commonality of cross-cultural doctrinal claims. This was true perhaps in the case of such writers as Huxley, Watts, and Otto, whom Forman singles out. But for Schuon and others of the perennialist school, whom the editor has surprisingly neglected to mention, the ultimate unity among the religions and their several spiritualities transcends all dogmatic and discursive formulations and lies precisely where Forman is looking, in the domain of pure intellection.”