More simply put, failures in perception are precisely indicators as to the fullness of experience itself for phenomenology, because phenomenology is focused on the content of experiences not as just a general stuffing for form, but as distinct instances that have the power to make the usual working of perception take a singular detour. The most extreme way of putting this (and I do so by using all these terms less technically) would be to say that, to a degree, phenomenology allows for experiential content to make the form of its own perception.
Or, in even more plain and less burdened language: phenomenology allows for something in experience to cohere such that it generates thereby the terms of its own coherence. (This is largely because what I am describing here is simply the reduction: to take up, theoretically, a "failure" is the beginning of a suspension of the natural attitude.)
However I explain this, what's clear is that this quality makes phenomenology fall into places where more formal theories of perception just don't have anything to say--or, quite frankly, don't want to say anything. Though its aims are much more lofty (and problematic, as its goal is nothing less than the complete reappropriation of this sphere to philosophy), this often makes it work a bit a posteriori, almost a bit empirically, without being beholden to the oppositions these two terms usually enter into.
There is a story that someone came up to Sartre who was eating something like an ice cream, and told him with phenomenology he could describe the ice cream--this is what got him exited about it. For me it was very similar, though without the more militant desire to oppose this sort of everyday reality to the high philosophies. If one goes too far with this way of looking at it, one easily makes the mistake (and it is often made by those who don't know phenomenology but want to criticize it) of thinking that phenomenology is a going back to the self-evident, the common sense, the ordinary, when (see Husserl, Ideas I §32) what is at stake is the making-scientific or theoretical of the assumption of self-evidence, an estrangement that brings something like the eating of the ice cream into the theoretical. So, without this militant edge, for me, what is important is the more basic fact that phenomenology can begin to rigorously investigate as completely normal what other theories consider aberrant.
As I said, I took up interest in the body, and this was mostly because that is where a lot of these "aberrations" in perceived or experienced content took place: the double-touch, tricks of perspective due to one's bodily stance, afterimages and the structure of the eye etc. etc. But as you can see, the interest began to take the form of wondering what was special about the phenomenon that it could fall into this particular place all the time--as I said, what was special to me was the forming power of the phenomenological content, or its sort of self-generating coherence, even if it is an aberrant perception. I'll pick this up next time as it took the form of a meditation on finitude, helped by Heidegger (then on to non-phenomena, like writing).
This will lead us to another use of phenomenology, one that will emerge from what I am talking about here, which is essentially what Husserl calls "immanence," and moving towards the being of the phenomenon itself--the fact that (and this is really what "immanence" is about for Husserl) its own limit is its condition for emergence. Posted by Mike Johnduff What is written about: Husserl, Merleau-Ponty