asked a series of questions that I've been meaning to get to. So, here is a response (sorry for the lateness):
That might be a provisional way of putting it.
Phenomenology is primarily a matter of describing the appearing of beings (or the lack thereof, in Heidegger's later thought). It does not try to create arguments for the existence of beings or about their essence, but tries to accurately describe how beings appear prior to any propositions or logical constructs. This, of course, is difficult because, for us philosophers, we already inhabit a world of propositions and are at least minimally trained in logical thought; for the non-philosopher these conceptions (and misconceptions about these conceptions) are still important for our social context. These affect how we inhabit our world in many ways and will inevitably influence the appearing of beings (for better or worse). Because of this, phenomenology is no simple empiricism or a naive 'perspectiveless' viewing of the world. Rather, phenomenology tries to see the world from where we already are, biases and all, because even there beings appear. It is a mistake to believe that beings appear only in the realm of apodictic certainty.
Descriptions cannot be argued; the only proper response to a description is a counter-description. One of Heidegger's primary descriptions is that beings must appear prior to any proposition; in other words, we cannot make true propositions about beings without those beings first appearing before us. Furthermore, we cannot make propositions unless we ourselves are in the truth; if we were perpetually in 'falsehood' we could not utter truth (compare this with Han's treatment of Nietzschean truth and Guignon's treatment of authenticity). The fact that he calls this a 'truth' (aletheia) is secondary to the description: is this an accurate description of our access to beings? Hence, one cannot 'refute' phenomenology with logical argumentation; rather, all that one can do is give a counter-phenomenology, a counter description of how beings appear. This is an important aspect of my claim, given to Tim earlier, that there are things we can talk about that are prior to logic and rationality, even things that ground logic and rationality.
This does raise the question of the utility of phenomenology. It actually is quite simple: if there is some connection between how beings appear and how beings are in their being (and do we have any reason to think otherwise? Any such thinking will itself gain its meaning from the need for it to be so), then having an accurate description of how beings appear is vital for having a cogent philosophy. If it is the case that beings do not appear as substances with properties (or at least do not at first appear as such), then we must find an alternative way of describing beings, as the substance/property mode of description will be inadequate, incomplete. Heidegger's description of the substance/property metaphysic as a de-worlded understanding of beings has important consequences for ontology: we cannot privilege one mode of understanding above another, especially if the currently predominant metaphysical trend (i.e. substance/property metaphysics) is understandable only on the backdrop of a subject within the world. The question, then, is not that of arguing for or against Heidegger through logic or reason, but providing a counter-description wherein the de-worlded understanding is seen as prior to (and fundamental for) the worlded understanding.
"a thing's essence is at least partially constituted by its relations with other beings and intentions."
I would totally agree with this. I have noticed that when I observe things essence is a unity. No one thing is separated from another, the objects that we observe are not independent of one another. We observe a differentiated unity, not distinct objects. Does this approach what Heidegger means by "pre-essential essence,”?
There are a few things that need to be clarified: a being's essence is constituted in a context, which context necessarily requires other beings, purposes, motivations, and such. The Rook's unity is not found in some 'objective' world, apart from certain norms and motivations, but in the engaged context of chess. Simply having chess pieces 'objectively' laying by a chess board is not sufficient for the pieces and board to have meaning; neither is its meaning fully constituted by the rules of the game. What is needed is a being who can unify them within the 'game' that we call chess. The rules have their meaning because they are informed by the motivation of winning, of "gaining the upper hand" in the game, etc. Hence, it is not quite so much that "[n]o one thing is separated from another," but that a being is unintelligible without it having some context in which it is disclosed. Beyond that clarification, I think you are heading in the right direction (assuming, of course, that I'm right).
The question of the "pre-essential essence" is not quite the same issue, though. That term comes from Heidegger's "On the Essence of Truth." A being's pre-essential essence is the practically unlimited ways that it could be disclosed, both by beings with Dasein's mode of comportment or otherwise (some alien race, perhaps, or animals). It is not understood as some essential 'nature' that we can 'see' in its 'properties,' as this is a de-worlded and, for that reason, diminished grasp of beings. The pre-essential essence of beings lies in its transcendence, its excess that cannot be captured in any given disclosure of that being, the object's ability to be disclosed in an indeterminate number of ways and, by such, its ability to surprise us. To put it one more way, the pre-essential essence is the admittedly negative description that we give of beings prior to any given disclosure of beings (see again here). In the latter we find a given being's relational character with other beings, purposes, motivations, etc., whereas a being's pre-essential essence is non-relational, it has not yet been articulated within a context. If we accept this description, then there is an important distinction between a being's relational character to other beings within a context and the pre-essential essence of that being, one that is incredibly important for Heidegger's later work.
However, when we think about what we have observed, this essence is broken up into objects of thought. (I would propose this happens because the essence is infintie and we are finite) When we think about these objects we cannot completely reproduce the context that they were in (ie the unity of essence) so we choose from this essence what is important for the moment. Is this what is meant by presencing here?
I guess I don't quite know what you mean by "objects of thought," but what you describe does fit into the notion of presencing. To presence an object in terms of, say, its color is to make its color salient and cover over its other (irrelevant) aspects. But even this 'breaking up' of the object's unity as found in another context (such as a game) will still bring the object to light in a context--that of colors, which includes luminosity, tints, shades, ambient lighting, etc. But in doing this it is not quite right to say that we "choose from this essence [or pre-essential essence] what is important for the moment." A better way to put it is that we open ourselves to the relevant aspects so that, if they are present, they can appear. Here is a useful quote from Heidegger's "Letter on Humanism":
Man does not decide whether and how beings appear, whether and how God and the gods or history and nature come forward into the clearing of Being, come to presence and depart. The advent of beings lies in the destiny of Being. But for man it is ever a question of finding what is fitting in his essence that corresponds to such destiny; for in accord with this destiny man as ek-sisting has to guard the truth of Being. Man is the shepherd of Being. It is in this direction alone that Being and Time is thinking when ecstatic existence is experienced as "care" (cf. section 44 C, pp. 226ff.).
"Letter on Humanism," in Basic Writings, 234.
What man does is find a "fitting" affectivity in relation to being by putting himself in such a state (bodily, emotionally, socially, etc.) wherein beings can appear in a particular way. Obviously, in some contexts this receptivity may take much time and practice, as in the master's grasp of relevant moves in a chess game or an art critic's grasp of good art: they cannot clearly codify their modes of seeing and judging objects, but they can tell you when they see them. In short, my primary issue with your description is the ambiguity in the "choosing": the master does not choose what appears, as if he is trying to force his will on beings, but attunes himself to what he wants to see so that, if it is there, it will be presenced. After writing that I see that there are actually a few levels going on here (including a rather intricate interplay between 'conscious' and 'unconscious' [though I don't care for that word at the moment] aspects of this description), but I do not have the time to examine that further.
I am just trying to get a feel for the unfamiliar vocabulary and for Heidegger's main points to see if the ideas he has would be worth wading through the obscure writing style.
Any suggestions on good clear commentators that could provide an introduction would be welcomed.
I don't know how clear the above was, but I feel, in my admittedly bias view, that it is worth it. The best move you could make is to become familiar with clearer descriptions as found in some of Heidegger's commentators. Understand that Heidegger was trying to do something new (or at least new to him; Clark Goble has written a few times on how Heidegger is not entirely novel, which is to be expected), he stumbles a lot, which he readily admits to in his later critiques of Being and Time, and his use of terminology, while perhaps unfortunate, also serves a purpose. I hope the above was helpful to you; it certainly was for me.
