Heidegger's world view is unfamiliar and difficult to understand. It is, in truth, profoundly different to the prevailing western view of what constitutes 'the world'. This digression is an informal, simplistic addition to my brief commentary on §15-16.
Unless you're viewing this Website in a text-only browser you can't have failed to see the road signs that illustrate its pages (even if you haven't actually used them to find your way about). Perhaps you first actually took notice of them when you saw the one headed 'Worldliness in General' located before §15? That sign won't have displayed properly. Perhaps when you saw it you were annoyed and even clicked your browser's 'Refresh' button to try to make it look right. I hope so, because if you did the world has made itself known to you.
But before worldliness is laid bare, a few thoughts about some of the key terms in Heidegger's esoteric vocabulary...
Looking at this Website and finding your way around it is not
a theoretical exercise. Certainly its content is largely theoretical, but actually
reading it and jumping from page to page is a practical activity about which
you hardly think at all. This unthinking way of doing things is the way we all
relate to the world most of the time. Unthinking, but with an end in sight.
This is Heidegger's 'heedful circumspection'.
In §15 Heidegger spells out what 'handiness' means. Useful things are always interconnected by innumerable 'references', and this whole complex web is necessarily known in advance of any single item in it. Indeed, an object can only show up because it makes sense within this larger whole.
So, consider the computer on which you are viewing these words. As you read them you implicitly recognise (though almost certainly fail to think about) the following:
These five headings (which are by no means of equal importance in Heidegger's analysis) gather together the myriad 'references' that make any piece of equipment usable. This is the way things are 'in themselves', Heidegger maintains. First and foremost things are 'ready-to-hand' or, in other words, useful and used.
At first sight this description of the way things fit together seems unexceptional but it is the claim that practical engagement with useful things is more fundamental than any detached observation of the world that is so startling. It really does turn things on their head.
Heidegger does not deny that detached observation of worldly objects is possible. How could he? But he will not grant this objective view the privileged status that it is popularly accorded. If, in a moment of curiosity, you consider the way your computer actually works Heidegger says that you are dealing with it in a 'deficient' way. You are merely looking at it rather than using it and have, in effect, removed it from the world.
So we can look at things or use them. There are two contadictory accounts of this fact:
The first option would be the popular choice but it is the second that is Heidegger's. He maintains that a detached, objective view of the world is not fundamental and is, in fact, made possible only on the basis of everyday, background, practical coping. In turn both ways for objects to be (used or observed) is dependent on a third way of being, namely 'existing', which is the way of being for people. The world, for Heidegger, is not a repository of objects, amongst which humans are to be counted. Rather, a correct understanding of the world must accommodate the way things actually are and, as part of this, it must incorporate the distinctively human way to be from the outset.
So things are truly themselves when they fail to show up. You are understanding your computer best when you view this or any other file and fail to notice the machine at all (which happens most of the time). But doesn't that render an analysis of the content of Heidegger's world impossible? Either you observe things objectively and fail to see them as they truly are or you use them as they are 'in themselves' but then they are, to all intents and purposes, invisible.
Fortunately there are circumstances when the world, in Heidegger's sense, becomes visible. When equipment is unusable, missing or in the way - and its use thereby disrupted - things and their reference relations are shown forth in the midst of our heedful circumspection. So if you were to grow frustrated by the incorrectly displayed sign at the beginning of §15 of this site and try to put it right by refreshing the page you would 'see' the presence of an item in the world (the sign) without merely looking at it. And as you saw it just 'lying there' not doing what it should, its links with its whole context would become apparent and the reference structure of the world would come into view. (I might have made this point more forcibly by having my Website deliver some horribly destructive virus to your machine. Then you would experience a disruption that you simply could not overlook and the objective-presence-in-the-midst-of-handiness that shows forth the world would be all too obvious. But I don't know how to do that, and you wouldn't thank me if I did.)