What launches transcendental phenomenology is the recognition that those modes of unity correlate with each other and with a third mode of unity, in ways that are tantalizingly asymmetrical. These three onenesses are: the factual unity of things and states of affairs, the eidetic unity of essences, and the living unity of consciousness as it flows along in a stream of experiences. Each has, and exhibits, its own distinctive kind of identity and persistence. Factual and essential unities give objects to the straightforward regard of consciousness, entering it as items of experience, each in its distinctive way; but consciousness can also deflect its regard back onto these enterings and discover its own unity, which is unlike either of theirs.
The possibility of this complex correlation is provided by the "principle of principles": that intuitions come on to us with distinctive boundary-conditions that we can accept as sources insuring the correctness of our knowledge of them. Or in Husserl's formulation:
"… that every originary presentive intuition is a legitimizing source of cognition, that everything originarily (so to speak, in its "personal" actuality) offered to us in 'intuition' is to be accepted simply as what it is presented as being, but also only within the limits in which it is presented there" (44).
The different kinds of unities have different kinds of edges, and these give away what kind of a unity each of them is going to be. But it's easy to miss the differences. That happens in the natural attitude, Husserl says, when all the objects of consciousness are taken as if they were factual items. Husserl complains that even his Logische Untersuchungen have been misunderstood as advocating just this error of "Platonic realism," by those who read into his use of the term "object" the implication that, through a perverse hypostatization, every thought turns into a thing (# 22). On the contrary, he says, the eidetic reduction, operative already in LU, empowers him to differentiate between how essences appear, and how cases appear.
Now with Ideen I, this distinction is sketched in beautiful detail. You can tell when the object occupying your consciousness is a physical thing, because things don't give themselves to you all at once. What you get instead is a perspective inviting you to move around to the other side to perceive some more of the thing. All the while the thing keeps its unity to itself, as the reference point of all the angles it gives to you, and out of which you must reproduce or copy or simulate the unified thing as you conceive it. But in conceiving, you don't have to put an "and" between two separate perceptions, the north face of a building and the south face, in order to yield the perception of the building as if it were a sum. These different views are given to you as continuous, as views of one thing.
Husserl terms this "shading off" or adumbration. (The notion of off-shading is reminiscent of a multiple-exposure photograph that captures successive phases of a movement in a single frame. Such photos were being seen for the first time at the turn of the century. Husserl also mentions new media such as the stereoscope and the cinema.) In contrast, essences give themselves to you all at once. Their boundaries are not sides, but rather laws entailing the characteristic necessities and possibilities of kinds of things (more about which below). The unity of any particular essence coheres within that determinate outermost boundary which free imaginative variations of possible cases must not exceed if they are to remain cases of this particular kind. Essential unity is centripetal, so to speak.
Then are those other unities–the ones presenting themselves as extended or factual–to be termed centrifugal, inasmuch as each spins off appearances in all directions from an inaccessible center? No, for their off-shading appears contextualized, as a foreground; and even as we focus upon the foreground it pulls its background into readiness for perception as soon as attention may shift to it. Every one is surrounded by a halo of and's, and beyond that are other somethings, seemingly without end. Whatever is extended is inexorably connected to whatever else is extended. (This last formulation, by the way, is an instance of an eidetic law. But the shift of attention that brings this essential rule into view is an eidetic reduction, and it wrenches us away from our naive attention to instances of things naturally appearing, under consideration here.) Every perception "motivates" another, stretching on toward expanding horizons.
The shift to the transcendental attitude–that is, the phenomenological or transcendental reduction–brings to Husserl's notice a third kind of unity, which discloses the off-shading of things in a startling new way. We notice now that what is adumbrated is spatial, but the adumbration itself is not spatial. It arises in consciousness. "Abschattung ist Erlebnis" (95), while what is adumbrated, das Abgeschattete, has to be something spatial. The off-shading of things is at the same time the streaming of conscious life. Peculiarly, the giving off of partial perceptibilities (by the thing) coincides with the taking up of partial perceptions (by streaming consciousness). Which one is doing the shading? Agency cannot be imputed absolutely to either side.
But on the "side" of consciousness, as it were, we now recognize that we are dealing with more than a progression of life-bites strung together in series with and's. The stream of conscious life is not a sum or aggregate; nor is it a generalization. That is, it exhibits a unity unlike either the sachverhaltig unity of a factual case or the eidetisch unity of an essence. Husserl must account for that unity, which he calls an ego, Ich.
Moreover, and of paramount significance, with the benefit of the transcendental reduction it can now be told that these three kinds of unities themselves are not connected merely in series, with and's combining them, as if they were three discrete somethings. Their relationship is vastly more subtle. In order to understand it, through reduction we try to isolate unity from what accounts for unity. (We are not looking for something "prior to" unity — such as some "cause" of unity –, because we can't have priority without having the number one, and oneness is just what is in question.)
Isolating oneness from the live experience-stream means removing the individual subject (you or me or Napoleon or whomever) from consideration. What is left, says Husserl, is transcendental subjectivity, "the pure act-process with its own essence" ("das reine Akterlebnis mit seinem eigenen Wesen"). (Paradoxically, we can see, right here in this formulation, that the reduction has not at all done away with essence, with states of affairs, or even with identity. We still have Eigenheit and Wesen, set in relation within a sentence. But these are now supposedly purified.) Husserl likens this de-individualized ego to a ray (# 92) or glance (# 101). Characteristically (or essentially) it has two poles or directions: the noematic and the noetic (from Greek terms noema and noesis, indicating what is thought and the act of thinking, respectively).
Husserl's discussion of "noetic-noematic structures" fails in its attempt to show how the ego reaches and secures both the unity of the known object, and the unity of the knowing subject. But it fails in a spectacular starburst of insight. Husserl notices that the mental stream has its own distinctive kind of adumbrations or continuities, which are more complex than those discussed above, the relatively simple off-shaded appearings of spatial objects in perception. Beyond that simple sort of off-shading, consciousness can also turn back on itself and reflect upon its own intending acts, or on any component thereof. The stream meanders among spatial objects, but can also at whim objectify aspects of its own acts of intending, and consider them. This yields a thick layering of possible objects (# 97). For example, here are some noemata that might enter the live experience stream: pencils … writing … German verbs … the frustration of strong verbs … Ulrike … memories in general … the unreliability of memory … components of perceptions … the advisability of analyzing perceptions into their components … the smell of popcorn wafting into the study … the effort to resist distractions … and so forth.
Some of these arise directly from things, while others arise as objectifications of what was inherent a moment ago in the very act of knowing, the noesis. How can we tell the difference? Husserl answers that you can tell when the ego-beam has penetrated through to the bottom of the stack of noemata, so to speak, and has gotten ahold of a thing itself, because at that point, all the aspects of the thing are known immanently–really–in the act of perceiving as being contained in the sense of the thing (# 98). For example, you know popcorn itself when you are perceiving the taste of butter and salt. (You do not know popcorn when you read this sentence; instead, you are reflecting on what it is to know popcorn, and popcorn's qualities are not given immanently within your object. But then while tasting popcorn, saltiness was given immanently but not objectified.)
Husserl rightly points out that we are able to slide up and down the pole of the ego-beam at will, moving now toward the thing, now away from it to consider the act of knowing and its modalities. For example, noematically I can consider a certain cat who probably exists, but then I can turn back noetically to assess the degree of certitude that characterizes my consideration of that selfsame cat as existing (# 105). Now if we were to slide down to the point where all modalities are behind us on the noetic side of the pole, and if there we were to face the object, we would get the pure sense of the object in which its unity is given.
In # 102 Husserl claims that this can happen, and that we can indeed slide far enough toward the object that the unity of the noema will be known as not having been imposed by the act of knowing. At that point, all of its qualities supposedly will be given immanently, really, contained in the perception rather than in the secondary conscious act that may grasp it a split-second later. Its sense will have been captured as something known with certainty to comprise its qualities, without the interference of a synthetic conscious act. (If this worked, it would effectively ensure the objectivity of knowledge, and would win the day for realism against idealism.) Husserl writes:
"The noematic objects … are unities transcendent to, but evidentially intended to in, the mental process. But if that is the case, then characteristics, which arise in [those unities] for consciousness and which are seized upon as their properties in focusing the regard on them, cannot possibly be regarded as really inherent moments of the mental process" (248-249).
Rather, they inhere in the object's sense, and subsequently are lifted out for analysis in the mental process.
The ambitiousness of this claim is matched by that of another, which has to do with the opposite end of the ego-pole. In # 108 Husserl says that we can also shinny far enough up the ego-pole that we can capture the affirming noesis in its purity. All the modalities will have been loaded over onto the side of the noema, and the no_sis will be a believing affirmation, pure and simple: an unqualified yes. Thus Husserl insists that there is a crucial difference between (a) being validly negated and (b) not-being. For example, he would distinguish (a) denying correctly that my spayed cat has a kitten, from (b) affirming that the kitten of my spayed cat is a non-entity. With (a), the negativity inheres in the noesis, which has not yet been purified of all modality; but with (b), the noesis would be pure affirmation (# 104).
How correct is Husserl's argument? We must grant that whatever makes this particular kitten impossible inheres elsewhere than in my knowing about it, for my denying something can't make it go away. Furthermore, there's nothing to prevent my forcing myself to think positively the thought of the kitten that my cat never had. Such a noetic posture is at least conceivable. However, its mere possibility is not enough to accomplish Husserl's purpose. Husserl needs to show that this pure affirming belief really is done, somewhere somehow, in the toughest case, the case of an intrinsically impossible entity such as the kitten of a spayed cat. (That is, has anyone succeeded in recapturing that magic moment of purely affirming noesis with regard to an intrinsically impossible object? And if so, how would one go about certifying the accomplishment?)
Unfortunately, neither end of the ego-ray connects as Husserl had hoped. At the noetic pole, the purely affirming ego eludes the grasp of consciousness; so does the pure sense of the thing itself, at the noematic pole. These terms may remain as ideal asymptotes toward which the ego-ray continually points while continually falling short. The successful recovery of the connection between knowing and reality awaits another strategy, to be mounted by Husserl in the posthumously published second volume of Ideen.