by Ven. Ariyavaṃsa
“‘loko, loko’ti, bhante, vuccati. kittāvatā nu kho, bhante, lokoti vuccatī”ti?
Venerable sir, it is said ‘the world, the world.’ In what way, venerable sir, is it said ‘the world’?
Normally, when people think of “the world” they are referring to everything, every thing. But what is this if not the totality of all things that are to be found within the world? If, however, one takes the trouble to consider this idea, it should not be long before one notices that it is deeply problematic, since it presupposes a world within which things can be found so that one can then add them together to get to this world, which one has already presupposed.
Martin Heidegger offered a radically different conception of the world. In Being and Time, he introduced the idea that the world is not another thing within-the-world, but is that because of which things are discovered.
the world is not itself an entity within-the-world; and yet it is so determinative for such entities that only in so far as ‘there is’ a world can they be encountered and show themselves in their being as entities which can be discovered.
BT p.102 
The phenomenon of ‘world’ is such that it makes all phenomena intelligible as the phenomena that they are. It is because of this world that things are significant. And things are always significant. Even something that I have never encountered before and that I cannot recognize in terms of my past experience—even this strange alien entity is determined as significant (in the words of Venerable Ñāṇavīra (2010: 266): “as ‘strange object, to be treated with caution’”). Experience is always the experience of something significant, and this significance is determined by the world, by the background of meaning-relations that forms the context within which entities are discovered. The world and the entities within-the-world are co-given. They arise together, mutually dependent, bound up with each other, and utterly inconceivable without each other.
Even this thought: “this world, which is that on the basis of which things can be discovered”—even this is a phenomenon which can only be there because of the background of the world which makes this statement meaningful. Notice that the distinction we are making here, between entities within-the-world and the world, is the same as the distinction we find in the suttas between determined things (saṅkhatā dhammā) and that which determines these determined things—determinations (saṅkhārā). But care is needed here—although we can distinguish between the world and those entities within-the-world whose significance is determined by the world, this does not mean that the world is not also an entity. Whenever we think “world”, we are designating some entity. If it were not an entity, then it would be some kind of eternal God-like extra-temporal cause for all things. But the Buddha said: sabbe saṅkhārā aniccā (e.g. MN 35). The world, which is that which determines determined things, is not eternal. This can be verified by my own experience. In reflexion I discover that the world can only ever be found as already being there, given—and since I had nothing to do with its arising, I also have no control over its passing away. And since I have no control over it, it is subject to disappearance at any moment. It is impermanent. That on the basis of which phenomena within-the-world are discovered is itself a phenomenon inasmuch as it is impermanent, suffering, not-self, and should be abandoned. The phenomenon of world is different from phenomena within-the-world—it is more general, it is the background, it is peripheral, it is never in focus, it is that which determines the significance of whatever shows up within-the-world—and yet it is still a phenomenon, albeit a general, background, peripheral one.
“In the question which we are to work out, what is asked about is being—that which determines entities as entities, that on-the-basis-of-which [Woraufhin] entities are already understood…”
BT p.25-6 
Although Heidegger was arguably the foremost phenomenological philosopher of the twentieth century and although he succeeded in describing so many of the phenomena involved in human experience, he was a puthujjana. Therefore, he assumed that he and the things that he encountered existed. Unable to see an escape from bhava, he was unable to go beyond suffering. Nonetheless, his thinking is a useful starting point for one who wishes to access the Buddha’s teaching at a time when so many pernicious assumptions obscure one’s ability to see the nature of experience. Let us, therefore, look at what Heidegger thought, before we later try to see where he went wrong.
Heidegger’s major contribution to philosophy can perhaps be described in terms of his attempt to transform the study of ontology, of being, and begins with what he called “the ontological difference”—the difference between beings [Seienden] and being [Sein]. Experience is always the experience of some being or other, some entity, some thing, some phenomenon. Having not seen the possibility of the cessation of being (bhavanirodha), Heidegger took the position, first articulated in the philosophy of the early Greeks, that in order to be able to attend to this or that being, this or that thing which is, first of all that being must be. Whether it is a chair, a headache or a vague impression about the day ahead, despite the fact that these things are all quite different, what unites them all is the fact that they all are. But this fact that they are, their being, cannot be understood as being just another being, since then we would have yet another being which is, and the being of this new being remains unaccounted for. Being is not just another being, another thing which is; and yet being cannot be understood without a being, since being is always the being of a being.
It is this idea, this distinction between being and beings, which allows for the possibility of the study of ontology—the study of being. For the most part, science studies the difference between beings and other beings. For example, biology studies “plants, animals, humans, life, etc.”, mathematics studies “numbers”, linguistics studies “languages”. Even though these are all abstract things, they are nevertheless things. They are all entities, beings, and so all of these sciences concern themselves with what Heidegger called the “ontic” (rather than the “ontological”) domain. Ontology, on the other hand, is only possible by making clear the distinction between being and beings. According to Heidegger, philosophy must be understood as that unique discipline which surmounts beings, in a quest to understand the being of beings. Philosophy, at least the philosophy that Heidegger set out to do, is the study of being—ontology.
We said that ontology is the science of being. But being is always the being of a being. Being is essentially different from a being, from beings. How is the distinction between being and beings to be grasped? How can its possibility be explained? If being is not itself a being, how then does it nevertheless belong to beings, since, after all, beings and only beings are? What does it mean to say that being belongs to beings? The correct answer to this question is the basic presupposition needed to set about the problems of ontology regarded as the science of being. We must be able to bring out clearly the difference between being and beings in order to make something like being the theme of inquiry. This distinction is not arbitrary; rather, it is the one by which the theme of ontology and thus of philosophy itself is first of all attained. We call it the ontological difference—the differentiation between being and beings. Only by making this distinction… not between one being and another being but between being and beings do we first enter the field of philosophical research. Therefore, in distinction from the sciences of the things that are, of beings, ontology, or philosophy in general, is the critical science, or the science of the inverted world. With this distinction between being and beings and the selection of being as theme we depart in principle from the domain of beings. We surmount it, transcend it. We can also call the science of being, as critical science, transcendental science. In doing so we are not simply taking over unaltered the concept of transcendental in Kant, although we are indeed adopting its original sense and its true tendency, perhaps still concealed from Kant. We are surmounting beings in order to reach being.
BPP p. 17
In Being and Time, we also find Heidegger stressing the transcendental nature of ontology.
Being and the structure of being lie beyond every entity and every possible character which an entity may possess. Being is the t r a n s c e n d e n s pure and simple.
BT p.62 
The ontological difference is always there, even when we are not making this difference explicit by studying ontology. Human beings, Heidegger thought, are that unique kind of being which holds open the difference between being and beings. Not only do we have an understanding of this or that being (e.g. I understand that this is my room, that this is my chair, that that is a tree outside the window, etc.) but we always already have an implicit understanding of the being of these beings which we encounter. This understanding of being, he argued, is a necessary precondition for any human comportment towards beings. It is because we have an understanding of being prior to the encountering of beings (not to say prior to any conceptualized science of being, or ontology) that we are able to project being as the horizon upon which beings are understood as the beings they are. Without this implicit, non-articulated understanding of being, the beings that we comport ourselves towards would simply be unintelligible.
To say that the “for-the-sake-of-which” and significance are both disclosed in Dasein, means that Dasein is that entity which, as being-in-the-world, is an issue for itself.
BT p.182 
Heidegger’s methodological approach to uncover the structure of being was to undergo an ontological investigation of that being whose being consists in an understanding of being. That is, his chief interest lay in the notion of Dasein, the being that he assumed that, in each case, we are. His whole Being and Time is described as an analytic of Dasein for the purpose of unveiling the structure of being. He assumed that this being that showed up as being the being that we are is in a different way from the other beings that we encounter. This led him to outline the different modes of being, the different ways in which different kinds of beings are. For example, when one adopts what Husserl called “the natural attitude”, entities are regarded as “substances”. This “substance ontology” derives from our implicit understanding of the notion of “substance”, which has been around since Aristotle and was later developed by Descartes who famously defined the term “res” as that which exists in such a way that it needs no other entity in order to exist. Making use of Heidegger’s favourite example, this hammer is made of a blob of iron and a wooden shank. Its properties can be measured and stated: its weight, its colour, its length, what it is made out of, etc. When I regard the hammer in this way it is such that it needs no other entity in order to be. It is independent, closed off, self-sufficient. This is what Sartre called “being-in-itself” and what Heidegger called the “present-at-hand”. This is its mode of being.
But there are, Heidegger thought, other ways in which a thing can be. For example, let’s say I’m a carpenter. The scientist’s positive descriptions of this hammer are of no interest to me when I pick it up and use it in order to make a table. While I use the hammer and go about my business of hammering, all of the positive descriptions of its weight, dimensions, etc. withdraw and become invisible. The hammer itself withdraws as I focus on my project of making this table. The hammer is simply a piece of equipment which I make use of in order to pound in nails and make this table which my client has asked me to make him. In using it, I do not need to explicitly think about it. In fact, as a carpenter I very rarely find myself thinking about the hammer as such. To do so may actually impinge on my work. Rather, the hammer is more like an extension of my own body. To grasp the being of the hammer in a way that most authentically discloses my use of it, we must understand it in terms of its in-order-to structure. This mode of being of “equipment” is what Heidegger called the “ready-to-hand” and it is such that it can only be understood in terms of other things. The hammer is in-order-to bang nails, the nails are in-order-to fix pieces of wood together, the fixing-pieces-of-wood-together is in-order-to make a table, and the making-a-table is in-order-to get paid by my client. And all of these relationships can only be understood in terms of a kind of superordinate in-order-to which defines my own goals, aims, motives—what Heidegger called the “for-the-sake-of-which”. The important point is this: for as long as I am a puthujjana, everything ready-to-hand is ready-to-my-hand—it always implies a me, a self, a person. Why am I making this table for my client? For the sake of being a carpenter. The “for-the-sake-of-which” I do things is nothing other than the understanding of the being that I am—sakkāyadiṭṭhi. And this understanding is always in terms of the ready-to-hand equipment that I circumspectively make use of. Everything which shows up for me does so in terms of ready-to-hand equipment that I can (or cannot) make use of “for-the-sake-of” being the being that I am. Things are always mine, for me, my concern, etc.—even if in some privative mode. For example, even someone else’s belongings present themselves as being not mine, not my concern, etc., and therefore are always found in some kind of relation to me, even though this relation is a negative one. Everything that I can possibly experience shows up as being already significant, already involved in my for-the-sake-of-which which is disclosed in my understanding of the world. But just as things are always understood in terms of me and my concerns, I can only understand myself in terms of things which I encounter. To put it another way, my understanding of the being that I am is always as being-in-the-world—a unitary phenomenon in which Dasein and world are given together and equiprimordial. One can only understand one in terms of the other.
Heidegger thought that even though we first encounter beings as being ready-to-hand, when we think about these beings, that which is proximally ready-to-hand gets passed over and entities are first and foremost conceived as a context of substantive things (res) which are present-at-hand. Substantiality becomes the basic characteristic of our philosophy of being, and we lose sight of the fact that substantiality is only made possible because of our being-in-the-world. Thus, rather than assuming that I am just another present-at-hand entity (as most people do), Heidegger comes closer to the truth by revealing the way in which the self is unveiled in its relation to ready-to-hand entities that I circumspectively make use of “for-the-sake-of” being that being which I have chosen to be. But he still takes this self at face-value and assumes that because that which is ready-to-hand comes with the significance of a “for me”, this “me” is to be found somewhere. He assumes that I am a being, and that this being which in each case I am is that being that has an understanding of being. Not having gone beyond sakkāyadiṭṭhi, he assumes—like all puthujjanas—that this understanding belongs to me. In order to unveil the particular mode of being of this being that he assumes he is, he gave it a new name: Dasein.
… [T]o work out the question of being adequately, we must make an entity—the inquirer—transparent in his own being … This entity which each of us is himself and which includes inquiring as one of the possibilities of its being, we shall denote by the term “Dasein”.
BT p.27 
Dasein, he said, is neither present-at-hand nor ready-to-hand, but is rather that being whose being involves an understanding of being. Heidegger describes Dasein’s particular way of being as follows:
Dasein is an entity which does not just occur among other entities. Rather it is ontically distinguished by the fact that, in its very being, that being is an issue for it.
BT p.32 
Whilst Dasein is the word he uses to describe that being [Seienden] which each of us in each case is, he calls this being’s particular mode of being [Sein] “existence”. The essence of Dasein lies in its existence—Ek-sistenz, literally: “standing beyond itself”.
The Dasein as such is being-toward-itself, being-with-others, and being-among entities handy [i.e. ready-to-hand] and extant [i.e. present-at-hand]. In the structural moments of towards-itself, with-others, and among-the-extant there is implicit throughout the character of overstepping, of transcendence.
BPP p.301 (my gloss in brackets)
Heidegger’s main point was this: the essential precondition required for an entity like Dasein to project a world and encounter beings (whether present-at-hand, ready-to-hand, Dasein, or any other kind of being) is the capacity to open up, to unveil, to disclose. Dasein provides the clearing—or, more precisely, it is the clearing—that opens up and makes possible the encountering of other beings. This is the essence of Dasein which its name already indicates. “Da” suggests a “here”, or a “there”, or “some specific place”. “Sein” means “to be”, and so “Dasein” is to be here, to be there, to be in some specific place. As Heidegger’s translator, Albert Hofstadter, explains in his appendix to The Basic Problems of Phenomenology:
The ontological role of the human being qua Dasien… is… to be the Da, to be its Da, namely, to be the essential disclosedness by which the here and the there first become possible, or by which the spatiality of the world becomes possible within which beings can be distinguished from their being and understood by way of their being and so encountered as the beings they are, so that human comportment toward them as beings becomes possible… Da is not just a here or a there or a here-there, but rather is the essential disclosure by which here, there, and here-there become possible. It is their source.
BPP p. 336
The end of the world, the end of being
upādānanirodhā bhavanirodho…pe…. evametassa kevalassa dukkhakkhandhassa nirodho hoti. ayaṃ kho, bhikkhave, lokassa atthaṅgamo.
With the cessation of assumption, the cessation of being… in this way there is the cessation of this whole heap of suffering. This, bhikkhus, is called the disappearance of the world.
We are now in a position to critically evaluate Heidegger’s thinking in the light of the Buddha’s teaching. He assumes that I am, and thought that the being that I am is disclosed in terms of the way in which the ready-to-hand entities that I circumspectively make use of in order to take a stand on my being comes with this significance of being “for me”. Up to a point, this is correct. For the puthujjana, everything ready-to-hand implies, indicates, points to me. Even that thought of “me” is there in the form of my thought. Whatever I look at, this me is always elsewhere. Why? Because this me is part of the background, the horizon that determines the significance of all the entities within-the-world that I encounter. What Heidegger was unable to see is the distinction between the puthujjana, the ariyasāvaka, and the arahat. For the arahat, the notion of “for me” no longer arises. For the ariyasāvaka, it arises, but he now knows that it is his mistaken assumptions in regard to this notion that are the cause of his suffering, and he knows the escape from this. For the puthujjana, the notion of “for me” is taken at face value. The mistake that Heidegger made—indeed, the mistake that every puthujjana makes—is to assume that all of the entities within-the-world that he encounters are in some way mine because, first of all, I exist. He assumes: “I exist, therefore things can be mine (or not mine).” The ariyasāvaka, however, understands that this is the wrong way round—it is only because things show up as being mine that the puthujjana assumes that I exist. The fact that I exist is a gratuitous assumption, based on the evidence of this ever-present notion of mine. However, even though this mine or for me keeps showing up, that is not because there is a me somewhere for which these things are. The ariyasāvaka knows that sabbe dhammā anattā—all things are not-self. This does not, contrary to most Buddhist commentataries, mean that there is no self or that the self does not exist. The self most definitely does exist for the puthujjana (due to the fact that he assumes that it exists). No—what it means is that whatever thing that I encounter, that is not self, since the self always shows up as being an aspect of the background which determines the significance of this thing. Self and world are inseparable.
Heidegger went a lot further than any other philosopher and was able to unveil many of the background phenomena that constitute our everyday experience—phenomena which we ordinarily pass over and fail to recognize. Indeed, the task he set himself was to unveil the most general of all background phenomena: being. His notion of the “ontological difference” opens up the possibility of discerning what the Buddha referred to as bhava. But the attempt to distinguish the being of different kinds of beings is a mistake based on his assumption that the self exists. Yes, things show up as being mine (for all who have not attained arahattaphala), but that does not mean that there is a being which I am. The whole notion of Dasein—the being whose being is characterized by its understanding of being—is misguided, and presumes some kind of prioritized centre of this experience, some kind of eternal entity beyond or outside this experience for whom the experience is for. Once one has made a distinction between being (bhava) and the things which are (dhammā) one only muddies the waters by trying to find the different kinds of being of different kinds of things. A stricter phenomenological approach would focus on being as such. Whether it is the being of this or that thing, being is there. And rather than assume that there is this being which I am whose being involves an understanding of being (i.e. that this understanding of being belongs to this being which is me), a stricter phenomenological description would say no more than “all experience involves an understanding of being” or “there can be no experience without an understanding of being”.
In fact, Heidegger had initially set out to disclose the meaning of being in general, being as such, but this led to his discussion of Temporalität which he touched on only briefly right at the end of Being and Time and attempted to flesh out in his lecture course The Basic Problems of Phenomenology. All of this was ultimately unsuccessful. Temporalität, an extremely obscure and problematic idea, was as far as his thinking at this time could go and it was at this point that he decided to give up on his analytic of Dasein and became more interested in the being of works of art. What became known as Heidegger’s “turn”, or the move from “early Heidegger” to “late Heidegger” does not require detailed discussion here, except that we can note that it was at the point where Heidegger tried to understand the meaning of being in general, bhava, rather than the being of this or that entity, that he reached his limit.
The division between the being of this and that entity, of me and of the objects that I encounter—all of this is a gratuitous mistake that stems from taking one’s own being for granted and giving it the position of the centre of the experience. Whether it is the being of Dasein, the being of something present-at-hand, the being of things that are ready-to-hand, or the being of anything else—being is there, bhava is there. This is what must be discerned and this, the Buddha tells us, is what must be brought to an end. So, how is this to be done? Heidegger was right insofar as the answer to this lies in developing an understanding of Dasein, in understanding what it is to be a puthujjana, and yet precisely because he was a puthujjana he was unable to grasp the entirety of the problem—to see it from an external perspective, as it were. The aim is not simply to understand more about what this thing is, whether I call it Dasein, or me, or my self. The aim must be to bring about an unalterable change in one’s understanding so that one abandons this notion once and for all. For a puthujjana, experience is always, at bottom, the experience of self and world and the task he must set himself is to bring about a radical and permanent transformation of this picture. In order to do this, his attention must include the background—that is, the world. The world of the puthujjana is always the world of things that in some way relate to me. The question is: is it possible to change the world such that things are significant (e.g. the hammer is still “for hammering in nails”) but their significance no longer includes the notion of a me for whom these things are for?
Worlds can certainly change. Thomas Kuhn (1970) demonstrated this rather nicely in his extremely Heideggerian account of scientific revolutions. Think of the shift from the Ptolemaic to the Copernican paradigm, or from the Newtonian to the Einsteinian. Paradigm shifts like this are nothing other than world-transformations. The old world collapses and is replaced by a new one. When an entity is encountered in a new paradigm, it is encountered on the basis of a completely new world, and so its significance is now completely different. A moving planet for an Einsteinian physicist means something entirely different from a moving planet for a Newtonian physicist, since the two inhabit separate and incompatible worlds.
So how does one change one’s world to the extent that the particular significance “for me” is eradicated—for if this were possible, then everything which one encountered in that world would be completely transformed? Fortunately, world-transformations are also possible for ontologico-existential worlds which are that on the basis of which things within-the-world are encountered. What must be recognized is that even the world (i.e. that thing which determines all things) is determined. Just as there cannot be any thing without a world, there cannot be any world without this body. If there were no body, no world could possibly arise, and so no entities whatsoever could be encountered. If this body were abandoned, then this world which arises dependent on this body can no longer stand. This is the end of the world that the Buddha talks of in SN 12:44—or at least the end of my world, the world which always discloses the way in which entities relate to me.
How, then, does one abandon the eye, the ear, the nose, the tongue, the body, the mind? All one can do is to keep pressing the thought that whatever thing I encounter, that can only be there because this body is already there, given beforehand.
‘atthi kāyo’ti vā panassa sati paccupaṭṭhitā hoti.
Or else the mindfulness that “There is a body” is present.
DN 22/ MN 10
Even that thought I have of what the ‘body’ is, or this ‘body’ which I see when I look down at my arms and legs, or this ‘body’ which I can feel touching the ground, or this ‘body’ which feels pain, or this ‘body’ which I am sitting down with and breathing with—whatever way in which the ‘body’ appears (as feelings, perceptions or intentions), that can only be there because body is already given. And that body is there with its consciousness. Rūpa and viññāṇa cannot possibly be accessed by me, cannot possibly be felt, perceived or intended, since they are that because of which there is feeling, perception and intentions, and yet I know they there because without them there would be no world, or any entity that can possibly be encountered within that world (including any thought in regard to my self). When one sees the contradiction involved in assuming the existence of a self whilst establishing the perception that anything which appears does so in dependence on something over which I have absolutely no control, then something must fall away. That body because of which I am in a world—this must be recognized… yathābhūtaṃ sammappaññāya sudiṭṭhaṃ hoti (MN 14). When it is well seen as it really is with right wisdom, it is seen as being beyond my control, always already there. And since its arising is beyond my control, so too it is subject to passing away at any moment.
“yaṃ kiñci samudayadhammaṃ, sabbaṃ taṃ nirodhadhamma”nti.
Whatever has the nature of arising, all of that is subject to cessation.
If the world were to cease (which it will), then nothing whatsoever will be able to be encountered any more. Even the idea of no more world, no more entities, death, nothingness—all of these are still phenomena, which have arisen against a background of a world. Without a world, even these would not be conceivable. And since the world is impermanent, so too anything that could possibly be encountered within that world is impermanent. And anything that is impermanent cannot possibly taken to be self, since the notion of a self is nothing other than an eternal extra-temporal entity which stands outside of this experience—as if such a thing were possible!—and which, being separate from this experience, has control over it. By developing the recognition that all things are impermanent, the self is squeezed out, with nowhere left to arise.
tasmātiha, bhikkhave, yaṃ kiñci rūpaṃ … yā kāci vedanā … yā kāci saññā … ye keci saṅkhārā … yaṃ kiñci viññāṇaṃ atītānāgatapaccuppannaṃ ajjhattaṃ vā bahiddhā vā oḷārikaṃ vā sukhumaṃ vā hīnaṃ vā paṇītaṃ vā yaṃ dūre santike vā, sabbaṃ rūpaṃ — ‘netaṃ mama, nesohamasmi, na meso attā’ti evametaṃ yathābhūtaṃ sammappaññāya daṭṭhabbaṃ.
Therefore, bhikkhus, any kind of matter whatsoever … any kind of perception whatsoever … any kind of determinations whatsoever … any kind of consciousness whatsoever, whether past, future, or present, internal or external, gross or subtle, inferior or superior, far or near, all consciousness should be seen as it really is with correct wisdom thus: ‘Not this is mine, not this I am, not this is my self’.
References from Pali Canon
DN Dīgha Nikāya
BT Heidegger, M. (1962) Being and Time. (trans. J. Macquarrie and E. Robinson). Malden MA: Blackwell Publishing Ltd.
BPP Heidegger, M. (1988) The Basic Problems of Phenomenology. (trans. A. Hofstadter). Bloomington IN: Indiana University Press.
Kuhn, T. S. (1970) The Structure of Scientific Revolutions (2nd Edition). Chicago: The University of Chicago Press.
Ñāṇavīra (2010) Clearing the Path. Path Press Publications.