Useful things are the objects we encounter in the course of our projects; like my laptop. They are always nested in a referential totality; a little like those Russian nesting dolls. Your pen, the paper, this table, these are all inner worldly beings that refer to one another and the project of being a student. The totality is like an empty structure that our specific projects fill in. Every totality has a “for the sake of which, which signifies an in order to, the in order to signifies a what for, the what for signifies a what-in of letting something be relevant, and the latter a what-with of relevance.”
Tools are “together... with...” For example, the pen goes together with your paper. Or think of game pieces, like chess; the individual pieces all exist within a referential structure. The pawn is not a piece of carved wood; it is a position within a structure. The activity of work always involves a totality; Heidegger’s example is production. Making a shoe implies the existence of one who will wear it. The actual production uses leather, nails, etc; the leather and the nails each refer to their respective sources, etc. Each of these pieces are interconnected; a totality is discovered.
Useful things are either handy or objectively present. Think about your experience when working intently on something. Furiously typing away on your keyboard, are you thinking about typing? Are you thinking about your keyboard? No, you’re not. The tool that you’re using recedes; it becomes transparent. This is the mode of handiness. This isn’t a significance that we project onto the entity; it is a mode of being. This is the way things are, initially and for the most part; everything just recedes into the background; this is how things are “in themselves.”
There are three possible ways this can change. Tools can become damaged or unusable; in which case, they enter the mode of conspicuousness. If your pen breaks or my laptop suddenly shuts down, they cease to be handy. It becomes objectively present. When a tool is missing, not in its proper region, our awareness of its absence discovers the properly placed parts of the totality as present; everything becomes obtrusive. And finally when something is in the way, when it is in a place it shouldn’t be, or when we don’t have time for it, what is to be taken care of is obstinate.
Conspicuousness, obtrusiveness and obstinacy bring to the fore the objective presence in the inner worldly beings at hand. This disrupts the chain of references; when your pen runs out of ink, the handy connection to the paper is disrupted. The referential structure of “for the sake of which, in order to,” etc, comes to the fore.
Part of the chapter on the worldliness of the world involves a discussion of Descartes’ notions of the world. Substance, and what not. I’m not going to pay much attention to this chapter except to point out something on page 89. I point this out because it relates back to Chris’s Nietzsche presentation. When Descartes describes the world in terms of substance, the sole access to this world is in terms of math and physics. What math makes accessible in a being constitutes its being. Remember the bridge example; Sturdy Gurdy holds up because the engineers used what amounts to brute force - an extremely solid structure. However, if the proper formulas were developed, than a bridge could be built that would “go with the flow.” Brute force would no longer be needed. In Descartes’ world, that formula would constitute the being of the bridge, rather than being an ontic description of it.
Ok, so I’ll toss in another brief recap here. Da-sein is being in the world. In this world, Da-sein enters into projects in order to understand itself; it encounters useful things that can either be disclosed as handy, or in breakdown conditions, objectively present. These inner worldly beings are always part of a referential totality; each thing refers to another thing.