seizing upon or neglecting possibilities

Section 4 of the Introduction to Being and Time contains a lot of preliminary characterizations of Da-sein that will be filled out later.

First Heidegger links up the terminology of Da-sein to human being. "As ways in which human beings behave, sciences have this being's (the human being's) kind of being.  We are defining this being terminologically as Da-sein. / Wissenschaften haben als Verhaltungen des Menschen die Seinsart dieses Seienden (Mensch).  Dieses Seiende fassen wir terminologisch als Dasein"

Next he claims that "Scientific research is neither the sole nor the most immediate kind of being of this being that is possible. / Wissenschaftliche Forschung ist nicht die einzige und nicht die nächste mögliche Seinsart dieses Seienden."

Scientific research is one way of being.  One conclusion we can draw, it seems, is that there are many kinds of being.  One kind of being is realized in scientific research, another kind weekends with your aging parents, and yet another kind of being deployed as a youth counselor at a Christian summer camp.  The notion that human beings play many different roles is is talked about in other disciplines. Georg Simmel's Web of Group Affiliations explained the emergence of individuality, of the phenomenon of 'self,' as the intersection of a plurality of roles that had no center or unifying motif other than the presence in each of them of this one thing, namely the individual itself. In each of my activities I deploy a certain kind of being.  It's really quite different how things work, what I and others around me are expected to do, all the way down to what gestures or tones of voice are used, when I work as an insurance agent as compared to life in my church or on weekends with the parents.  For Simmel, it's not that I take the same 'I' with me to each activity and then find a way to accommodate that to the discrete environments I encounter; rather my sense of being an 'I' is produced by the psychological fact that I do the various roles in my life, but the agent or carrier of these different roles, since it participates in all of them, cannot be reduced to each separate activity as adult son, insurance agent, or pathetic blogger.  We interpret this remainder, with plenty of help from institutions, as an 'I,' a subject' that is present in all manifestations but not reducible to them.  The richness of this essay by Simmel is certainly not conveyed here and if you haven't come across it before, I recommend it.

But Heidegger's interest is not in showing how a normal, common-sense notion of individuality, identity, and personhood is produced indirectly by Dasein's variety.  Heidegger takes the reflexive nature of Dasein as granted, as established.  He's not interested, here, in a historical or sociological account of where this reflexivity comes from.  Nor is he going to be interested in Fichte's efforts to establish the self and its reflexivity ontologically via the transition from Absolute being to finite being, and the concomitant positing of an other outside of me, outside of the Absolute, thus establishing my finitude, since I no longer contain the other now outside me, thus allowing finite being to become self-conscious of itself as a specific being.

And so: when Heidegger describes Dasein to us in these pages is he talking about something universal?  Something that transcends all that boring history?  Or is he a European philosopher and he's talking about European 'man' as things stand circa 1927?

Da-sein is a being that does not simply occur among other beings.  Rather it is ontically distinguished by the fact that in its being this being is concerned about its very being.  Thus it is constitutive of the being of Da-sein to have, in its very being, a relation of being to this being. And this in turn means that Da-sein understands itself in its being in some way and with some explicitness.  It is proper to this being that it be disclosed to itself with and through its being.   Understanding of being is itself a determination of being of Da-sein.  The ontic distinction of Da-sein lies in the fact that it is ontological.  (Section 4)
Das Dasein ist ein Seiendes, das nicht nur unter anderem Seienden vorkommt. Es ist vielmehr dadurch ontisch ausgezeichnet, daß es diesem Seienden in seinem Sein um dieses Sein selbst geht.  Zu dieser Seinsverfassung des Daseins gehört aber dann, daß es in seinem Sein zu diesem Sein ein Seinsverhältnis hat. Und dies wiederum besagt: Dasein versteht sich in irgendeiner Weise und Ausdrücklichkeit in seinem Sein. Diesem Seienden eignet, daß mit and durch sein Sein dieses ihm selbst erschlossen ist. Seinsverständnis ist selbst eine Seinsbestimmtheit des Daseins.  Die ontische Auszeichnung des Daseins liegt darin, daß es ontologisch ist.

But we're not to think, are we, that this Dasein is equivalent to our normal notion of a human subject?  Scientific research is one kind of being, being a bureaucrat in an office environment is another.  Heidegger's not trying to unite these different expressions of being.  He's not trying to get to the Absolute through the particular; the finite.  And so when he says that "it is constitutive of the being of Da-sein to have, in its very being, a relation of being to this being," he's not referring to the kind of self-relation that produces a subject.  It's just that when you look at all kinds of being, you see that "this being is concerned about its very being." Or am I completely wrong and Heidegger is indeed talking to us about the production of a modern, European, subject-object nihilist decadent Thomas Mann Death In Venice Buddenbrooks Magic Mountain kind of guy?

Thomas Mann's Magic Mountain / Der Zauberberg comes out in 1924. Young, impressionable, naive Hans has trained as an engineer, but he has no "calling" for it, the way Max Weber says you are supposed to.  He just kind of wanders into it in default mode.  But then he visits his cousin in the rest home for sick people up in the mountain – where everyone has pretty much stopped working, what with being so sick and all.  As young Hans puts it: "the dying are to be treated as though in enjoyment of a permanent birthday."  The problem is, however, that tuberculosis is such a chronic disease!  You can live with it for a long time! Why you probably can't ever really be said to get better! The moment one returns to "the world below" as it is called, complete remissions are transformed into sudden recurrences that send one back up to the "magic mountain." After more or less willing himself to be sick so he wouldn't have to go back to pointless land as an engineer, Hans interacts with some stock characters that represent different strands of European thinking. Settembrini is an Italian humanist.  By an accident of historical fate, I first read this book when Guido Sarducci was doing his hilarious imitation of an Italian preist on Saturday Night Live (you know, when it was still good, not like today, where they don't know from funny), and I have never been able to shake the picture of Guido Sarducci's character when reading Settembrini's speeches in Magic Mountain.  Settembrini is a product of the Italian Risorgimento – Italy, you know, became a European nation (if it ever did; this is disputed in Italy) quite late, in 1870.  Thus a more old-fashioned Enlightenment thinking, proud of reason and nationalist lived on for a while longer. Naphta's nihilism and skepticism about Enlightenment rationalism forms the counterpoint to Settembrini, and Hans flirts with one view, then another, but basically is a poor receptacle for such elevated discourse.  (And I have always thought that Mann's ability to include serious philosophic discussion in a novel like this was a sign of his greatness as a writer.)

Hans is second or third or fourth generation bourgeois in a capitalist and world economic revolution that's already being going on for a while. "Inheriting" a certain kind of spirit is thought to be crucial for the reproduction of society.  Joseph Schumpeter in Capitalism, Socialism, Democracy provides one version of what happens when this 'spirit' flags, and of course Max Weber in Protestant Ethic and the Spirit of Capitalism provides another.&Onbsp; Hans does not have that spirit!  Think of Hans and the argument from Weber and Schumpeter in the context of this passage:

Da-sein always understands itself in terms of its existence, in terms of its possibility to be itself or not to be itself.  Da-sein has either chosen these possibilities itself, stumbled upon them, or in each instance already grown up into them.  Existence is decided only by each Da-sein itself in the manner of seizing upon or neglecting such possibilities. / Das Dasein versteht sich selbst immer aus seiner Existenz, einer Möglichkeit seiner selbst, es selbst oder nicht es selbst zu sein.  Diese Möglichkeiten hat das Dasein entweder selbst gewählt, oder es ist in sie hineingeraten oder je schon darin aufgewachsen. (Section 4)

Here I start running into a problem. "Da-sein . . . understands itself . . . in terms of its possibility to be itself or not to be itself."

What does 'itself' mean here?  What does it mean for Da-sein to "be itself"? Has our protagonist from The Magic Mountain, Hans Castorp, chosen to be himself by refusing to seriously enter the engineering profession and spending his time playing sick at the sanitorium, or has he chosen not to be himself?