Martin Heidegger, the 20th-century German philosopher, introduced to the world a large body of work which intended a profound change of direction for philosophy. Such was the depth of change that he found himself needing to introduce a number of neologisms and adapted vocabulary, often connected to idiomatic words and phrases in the German language.
Two of his most basic neologisms, present-at-hand and ready-to-hand, are used to describe various attitudes toward things in the world. For Heidegger, such "attitudes" are prior to, i.e. more basic than, the various sciences of the individual items in the world. Science itself is an attitude, one that attempts a kind of neutral investigation. Other related terms are also explained below.
Heidegger's overall analysis is quite involved, taking in a lot of the history of philosophy. See Being and Time for a description of his overall project, and to give some context to these technical terms.
- (Ancient Greek: ἀλήθεια)
Heidegger's idea of aletheia, or disclosure (Erschlossenheit), was an attempt to make sense of how things in the world appear to human beings as part of an opening in intelligibility, as "unclosedness" or "unconcealedness". It is closely related to the notion of world disclosure, the way in which things get their sense as part of a holistically structured, pre-interpreted background of meaning. Initially, Heidegger wanted aletheia to stand for a re-interpreted definition of truth. However, he later corrected the association of aletheia with truth. See main article on aletheia for more information.
An assertion (as opposed to a question, a doubt or a more expressive sense) is apophantic. It is a statement that covers up meaning and just gives us something as present-at-hand. For Instance, "The President is on vacation", and, "Salt is Sodium Chloride" are sentences that, because of their apophantic character, can easily be picked-up and repeated in news and gossip by 'The They.' However, the real ready-to-hand meaning and context may be lost.
- (German: In-der-Welt-sein)
Being-in-the-world is Heidegger's replacement for terms such as subject, object, consciousness, and world. For him, the split of things into subject/object, as we find in the Western tradition and even in our language, must be overcome, as is indicated by the root structure of Husserl and Brentano's concept of intentionality, i.e., that all consciousness is consciousness of something, that there is no consciousness, as such, cut off from an object (be it the matter of a thought, or of a perception). Nor are there objects without some consciousness beholding or being involved with them.
At the most basic level of being-in-the-world, Heidegger notes that there is always a mood, a mood that "assails us" in our unreflecting devotion to the world. A mood comes neither from the "outside" nor from the "inside," but arises from being-in-the-world. One may turn away from a mood, but that is only to another mood; it is part of our facticity. Only with a mood are we permitted to encounter things in the world. Dasein (a co-term for being-in-the-world) has an openness to the world that is constituted by the attunement of a mood or state of mind. As such, Dasein is a "thrown" "projection" (geworfen Entwurf), projecting itself onto the possibilities that lie before it or may be hidden, and interpreting and understanding the world in terms of possibilities. Such projecting has nothing to do with comporting oneself toward a plan that has been thought out. It is not a plan, since Dasein has, as Dasein, already projected itself. Dasein always understands itself in terms of possibilities. As projecting, the understanding of Dasein is its possibilities as possibilities. One can take up the possibilities of "The They" self and merely follow along or make some more authentic understanding. (See Hubert Dreyfus' book Being-in-the-World.)
- (German: Sein-zum-Tode)
Being-toward-death is not an orientation that brings Dasein closer to its end, in terms of clinical death, but is rather a way of being. Heideggerian terminology refers to a process of growing through the world where a certain foresight guides the Dasein towards gaining an authentic perspective. It is provided by dread or death. In the analysis of time, it is revealed as a threefold condition of Being. Time, the present and the notion of the "eternal", are modes of temporality. Temporality is the way we see time. For Heidegger, it is very different from the mistaken view of time as being a linear series of past, present and future. Instead he sees it as being an ecstasy, an outside-of-itself, of futural projections (possibilities) and one's place in history as a part of one's generation. Possibilities, then, are integral to our understanding of time; our projects, or thrown projection in-the-world, are what absorb and direct us. Futurity, as a direction toward the future that always contains the past—the has-been—is a primary mode of Dasein's temporality.
Death is that possibility which is the absolute impossibility of Dasein. As such, it cannot be compared to any other kind of ending or "running out" of something. For example, one's death is not an empirical event. For Heidegger, death is Dasein's ownmost (it is what makes Dasein individual), it is non-relational (nobody can take one's death away from one, or die in one's place, and we can not understand our own death through the death of other Dasein), and it is not to be outstripped. The "not-yet" of life is always already a part of Dasein: "as soon as man comes to life, he is at once old enough to die." The threefold condition of death is thus simultaneously one's "ownmost potentiality-for-being, non-relational, and not to be out-stripped". Death is determinate in its inevitability, but an authentic Being-toward-death understands the indeterminate nature of one's own inevitable death — one never knows when or how it is going to come. However, this indeterminacy does not put death in some distant, futural "not-yet"; authentic Being-toward-death understands one's individual death as always already a part of one.
With average, everyday (normal) discussion of death, all this is concealed. The "they-self" talks about it in a fugitive manner, passes it off as something that occurs at some time but is not yet "present-at-hand" as an actuality, and hides its character as one's ownmost possibility, presenting it as belonging to no one in particular. It becomes devalued — redefined as a neutral and mundane aspect of existence that merits no authentic consideration. "One dies" is interpreted as a fact, and comes to mean "nobody dies".
On the other hand, authenticity takes Dasein out of the "They," in part by revealing its place as a part of the They. Heidegger states that Authentic being-toward-death calls Dasein's individual self out of its "they-self", and frees it to re-evaluate life from the standpoint of finitude. In so doing, Dasein opens itself up for "angst," translated alternately as "dread" or as "anxiety." Angst, as opposed to fear, does not have any distinct object for its dread; it is rather anxious in the face of Being-in-the-world in general — that is, it is anxious in the face of Dasein's own self. Angst is a shocking individuation of Dasein, when it realizes that it is not at home in the world, or when it comes face to face with its own "uncanny" (German Unheimlich "not at home"). In Dasein's individuation, it is open to hearing the "call of conscience" (German Gewissensruf), which comes from Dasein's own Self when it wants to be its Self. This Self is then open to truth, understood as unconcealment (Greek aletheia). In this moment of vision, Dasein understands what is hidden as well as hiddenness itself, indicating Heidegger's regular uniting of opposites; in this case, truth and untruth.
- (German: Mitsein)
Both modes of "present-at-hand" and "ready-to-hand," are distinguished from how other things are primarily encountered. While all entities (non-Dasein, other Daseins, and itself) are encountered in these modes, the mode of "being-with" and all the emotion, loneliness and togetherness that it implies, is a unifying mode of being for Dasein and its world.
Being-with is a nuanced concept for Heidegger, made especially difficult for readers because of his writing style and the challenge of translating his works into English. However, in describing the Dasein's fundamental mode of being-in-the-world as Care (German: Sorge), for example "Dasein cares about its own Being", it could be said that being-with is a fundamental way of understanding Dasein's character as a being that is interested in its world; it is not a secondary role, but a descriptive characteristic.[original research?]
Care (or concern) 
- (German: Sorge)
A fundamental basis of our being-in-the-world is for Heidegger, not matter or spirit, but care:
- Dasein's facticity is such that its Being-in-the-world has always dispersed itself or even split itself up into definite ways of Being-in. The multiplicity of these is indicated by the following examples: having to do with something, producing something, attending to something and looking after it, making use of something, giving something up and letting it go, undertaking, accomplishing, evincing, interrogating, considering, discussing, determining. . . .
All these ways of Being-in have concern (Fürsorge, care) as their kind of Being. Just as the scientist might investigate or search, and presume neutrality, we see that beneath this there is the mood, the concern of the scientist to discover, to reveal new ideas or theories and to attempt to level off temporal aspects.
- (German: Lichtung)
In German the word Lichtung means a clearing, as in, for example, a clearing in the woods. Since its root is the German word for light (Licht), it is sometimes also translated as "lighting," and in Heidegger's work it refers to the necessity of a clearing in which anything at all can appear, the clearing in which some thing or idea can show itself, or be unconcealed. Note the relation that this has to Aletheia (see the main article or the entry above) and disclosure.
Here is Martin Heidegger on philosophy as the task of destroying ontological concepts, in other words also including, ordinary everyday meanings of words like time, history, being, theory, death, mind, body, matter, logic etc.:
- When tradition thus becomes master, it does so in such a way that what it 'transmits' is made so inaccessible, proximally and for the most part, that it rather becomes concealed. Tradition takes what has come down to us and delivers it over to self-evidence; it blocks our access to those primordial 'sources' from which the categories and concepts handed down to us have been in part quite genuinely drawn. Indeed it makes us forget that they have had such an origin, and makes us suppose that the necessity of going back to these sources is something which we need not even understand. (Being and Time, p. 43)
Heidegger considers that tradition can become calcified here and there:
- If the question of Being is to have its own history made transparent, then this hardened tradition must be loosened up, and the concealments which it has brought about dissolved. We understand this task as one in which by taking the question of Being as our clue we are to destroy the traditional content of ancient ontology until we arrive at those primordial experiences in which we achieved our first ways of determining the nature of Being—the ways which have guided us ever since. (Being and Time, p. 44)
Heidegger then remarks on the positivity of his project of Destruktion:
- it has nothing to do with a vicious relativizing of ontological standpoints. But this destruction is just as far from having the negative sense of shaking off the ontological tradition. We must, on the contrary, stake out the positive possibilities of that tradition, and this means keeping it within its limits; and these in turn are given factically in the way the question is formulated at the time, and in the way the possible field for investigation is thus bounded off. On its negative side, this destruction does not relate itself toward the past; its criticism is aimed at 'today' and at the prevalent way of treating the history of ontology. .. But to bury the past in nullity (Nichtigkeit) is not the purpose of this destruction; its aim is positive; its negative function remains unexpressed and indirect. (Being and Time, p. 44)
Dasein is a German word and is sometimes translated as "being-there" or "being-here" (da combines in its meaning "here" and "there", excluding the spatial-relational distinction made by the English words; Sein is the infinitive, "to be"). Mostly it is not translatable at all. Heidegger, after Nietzsche, used the word, but as a synonym for "human being" or "human entity." A Dasein is then a new coinage for a human being that is there, in a familiar world, and in a mood. Dasein also has unique capacities for language, intersubjective communication, and detached reasoning. Furthermore, average humans have an understanding of being insofar as they understand what things are and that they are e.g. "My dog is brown" or "Today is Sunday." Heidegger believed that this pre-reflective understanding of being, that which determines entities as entities, helps constitute our unique existence as human beings, thus the coinage of "Dasein."
Disclosure, or "world disclosure" 
- (German: Erschlossenheit)
Hubert Dreyfus and Charles Spinosa write that: "According to Heidegger our nature is to be world disclosers. That is, by means of our equipment and coordinated practices we human beings open coherent, distinct contexts or worlds in which we perceive, feel, act, and think."
Heidegger scholar Nikolas Kompridis writes: "World disclosure refers, with deliberate ambiguity, to a process which actually occurs at two different levels. At one level, it refers to the disclosure of an already interpreted, symbolically structured world; the world, that is, within which we always already find ourselves. At another level, it refers as much to the disclosure of new horizons of meaning as to the disclosure of previously hidden or unthematized dimensions of meaning."
- (German: das Zeug)
An object in the world with which we have meaningful dealings with.
A nearly un-translatable term, Heidegger's equipment can be thought of as a collective noun, so that it is never appropriate to call something 'an equipment'. Instead, its use often reflects it to mean a tool, or as an "in-order-to" for Dasein. Tools, in this collective sense, and in being ready-to-hand, always exist in a network of other tools and organizations, e.g., the paper is on a desk in a room at a university. It is inappropriate usually to see such equipment on its own or as something present-at-hand
Ereignis is translated often as "an event," but is better understood in terms of something "coming into view." It comes from the German prefix, er-, comparable to 're-' in English, and Auge, eye. It is a noun coming from a reflexive verb. Note that the German prefix er- also can connote an end or a fatality. A recent translation of the word by Kenneth Maly and Parvis Emad renders the word as "enowning"; that in connection with things that arise and appear, that they are arising 'into their own'. Hubert Dreyfus defined the term as "things coming into themselves by belonging together."
Ereignis appears in Heidegger's later works and is not easily summarized. The most sustained treatment of the theme occurs in the cryptic and difficult Contributions to Philosophy. In the following quotation he associates it with the fundamental idea of concern from Being and Time, the English etymology of con-cern is similar to that of the German:
- ...we must return to what we call a concern. The word Ereignis (concern) has been lifted from organically developing language. Er-eignen (to concern) means, originally, to distinguish or discern which one's eyes see, and in seeing calling to oneself, ap-propriate. The word con-cern we shall now harness as a theme word in the service of thought.
Simply put, Heidegger uses this word only to denote the noun — that something is.
Two related words, existenziell and Existential, are used as descriptive characteristics of Being. To be existenziell is a categorical or ontic characteristic: an understanding of all this which relates to one's existence, while an Existenzial is an ontological characteristic: the structure of existence.
Often translated as "releasement," Heidegger's concept of Gelassenheit has been explained as "the spirit of disponibilité [availability] before What-Is which permits us simply to let things be in whatever may be their uncertainty and their mystery." Heidegger elaborated the idea of Gelassenheit in 1959, with a homonymous volume which includes two texts: a 1955 talk entitled simply Gelassenheit, and a 'conversation' (Gespräch) entitled Zur Erörterung der Gelassenheit. Aus einem Feldweggespräch über das Denken ("Towards an Explication of Gelassenheit: From a Conversation on a Country Path about Thinking" or "Toward an Emplacing Discussion [Erörterung] of Releasement [Gelassenheit]: From a Country Path Conversation about Thinking"). An English translation of this text was published in 1966 as "Conversation on a Country Path about Thinking". He borrowed the term from the Christian mystical tradition, proximately from Meister Eckhart.
"Being thrown" (geworfen) into the world. Geworfen denotes the arbitrary or inscrutable nature of Dasein that connects the past with the present. The past, through Being-toward-Death, becomes a part of Dasein. Awareness and acknowledgment of the arbitrariness of Dasein is characterized as a state of "thrown-ness" (Geworfenheit) in the present, i.e., being thrown into the world with all its attendant frustrations, sufferings, and demands that one does not choose, such as social conventions or ties of kinship and duty. The very fact of one's own existence is a manifestation of thrown-ness. The idea of the past as a matrix not chosen, but at the same time not utterly binding or deterministic, results in the notion of Geworfenheit—a kind of alienation that human beings struggle against, and that leaves a paradoxical opening for freedom:
- [T]he thrower of the PROJECT is THROWN in his own throw. How can we account for this freedom? We cannot. It is simply a fact, not caused or grounded, but the condition of all causation and grounding.
Heidegger uses the term ontic, often in contrast to the term ontological, when he gives descriptive characteristics of a particular thing and the "plain facts" of its existence. For example, the objects that are studied by physics or chemistry are ontic, they are certain given things in the world that are studied without necessarily raising more general ontological questions.
- (German: ontologisch)
As opposed to "ontic" (ontisch), ontological is used when the nature, or meaningful structure of existence is at issue. Ontology, a discipline of philosophy, focuses on the formal study of Being. Thus, something that is ontological is concerned with understanding and investigating Being, the ground of Being, or the concept of Being itself.
- (German: Möglichkeit)
A term used only once in a particular edition of Being and Time. In the text, the term appears to denote "the possibility whose probability it is solely to be possible". At least, if it were used in context, this is the only plausible definition.
- (German: vorhanden; Vorhandenheit "presence-at-hand")
With the present-at-hand one has (in contrast to “ready-to-hand”) an attitude like that of a scientist or theorist, of merely looking at or observing something. In seeing an entity as present-at-hand, the beholder is concerned only with the bare facts of a thing or a concept, as they are present and in order to theorize about it. This way of seeing is disinterested in the concern it may hold for Dasein, its history or usefulness. This attitude is often described as existing in neutral space without any particular mood or subjectivity. However, for Heidegger, it is not completely disinterested or neutral. It has a mood, and is part of the metaphysics of presence that tends to level all things down. Through his writings, Heidegger sets out to accomplish the Destruktion (see above) of this metaphysics of presence.
Presence-at-hand is not the way things in the world are usually encountered, and it is only revealed as a deficient or secondary mode, e.g., when a hammer breaks it loses its usefulness and appears as merely there, present-at-hand. When a thing is revealed as present-at-hand, it stands apart from any useful set of equipment but soon loses this mode of being present-at-hand and becomes something, for example, that which must be repaired or replaced.
- (German griffbereit, zuhanden; Zuhandenheit "readiness-to-hand, handiness")
However, in almost all cases we are involved in the world in an ordinary, and more involved, way. We are usually doing things with a view to achieving something. Take for example, a hammer: it is ready-to-hand; we use it without theorizing. In fact, if we were to look at it as present-at-hand, we might easily make a mistake. Only when it breaks or something goes wrong might we see the hammer as present-at-hand, just lying there. Even then however, it may be not fully present-at-hand, as it is now showing itself as something to be repaired or disposed, and therefore a part of the totality of our involvements. In this case its Being may be seen as unreadiness-to-hand. Heidegger outlines three manners of unreadiness-to-hand: Conspicuous (damaged, e.g. lamps wiring has broken), Obtrusive (a part is missing which is required for the entity to function e.g. we find the bulb is missing), Obstinate (when the entity is a hindrance to us in pursuing a project, e.g. the lamp blocks my view of the computer screen).
Importantly, the present-at-hand only emerges from the prior attitude in which we care about what is going on and we see the hammer in a context or world of equipment that is handy or remote, and that is there "in order to" do something. In this sense the ready-to-hand is primordial compared to that of the present-at-hand. The term primordial here does not imply something Primitive, but rather refers to Heidegger's idea that Being can only be understood through what is everyday and "close" to us. Our everyday understanding of the world is necessarily essentially a part of any kind of scientific or theoretical studies of entities — the present-at-hand — might be. Only by studying our "average-everyday" understanding of the world, as it is expressed in the totality of our relationships to the ready-to-hand entities of the world, can we lay appropriate bases for specific scientific investigations into specific entities within the world.
For Heidegger in Being and Time this illustrates, in a very practical way, the way the present-at-hand, as a present in a "now" or a present eternally (as, for example, a scientific law or a Platonic Form), has come to dominate intellectual thought, especially since the Enlightenment. To understand the question of being one must be careful not to fall into this leveling off, or forgetfulness of being, that has come to assail Western thought since Socrates, see the metaphysics of presence.
- (German: Entschlossenheit)
Resoluteness refers to one's ability to "unclose" one's framework of intelligibility (i.e., to make sense of one's words and actions in terms of one's life as a whole), and the ability to be receptive to the "call of conscience."
'The One' / 'the They' 
- (German: Das Man, meaning "they-self")
One of the most interesting and important 'concepts' in Being and Time is that of Das Man, for which there is no exact English translation; different translations and commentators use different conventions. It is often translated as "the They" or "People" or "Anyone" but is more accurately translated as "One" (as in "'one' should always arrive on time"). Das Man derives from the impersonal singular pronoun man ('one', as distinct from 'I', or 'you', or 'he', or 'she', or 'they'). Both the German man and the English 'one' are neutral or indeterminate in respect of gender and, even, in a sense, of number, though both words suggest an unspecified, unspecifiable, indeterminate plurality.
Heidegger refers to this concept of the One in explaining inauthentic modes of existence, in which Dasein, instead of truly choosing to do something, does it only because "That is what one does" or "That is what people do". Thus, das Man is not a proper or measurable entity, but rather an amorphous part of social reality that functions effectively in the manner that it does through this intangibility.
Das Man constitutes a possibility of Dasein's Being, and so das Man cannot be said to be any particular someone. Rather, the existence of 'the They' is known to us through, for example, linguistic conventions and social norms. Heidegger states that, "The "they" prescribes one's state-of-mind, and determines what and how one 'sees'".
To give examples: when one makes an appeal to what is commonly known, one says "one does not do such a thing"; When one sits in a car or bus or reads a newspaper, one is participating in the world of 'the They'. This is a feature of 'the They' as it functions in society, an authority that has no particular source. In a non-moral sense Heidegger contrasts "the authentic self" (my owned self) with "the they self" ("my un-owned self").
A related concept to this is that of the apophantic assertion.
Heidegger gives us four ways of using the term world:
- 1. "World" is used as an ontical concept, and signifies the totality of things which can be present-at-hand within the world.
- 2. "World" functions as an ontological term, and signifies the Being of those things we have just mentioned. And indeed 'world' can become a term for any realm which encompasses a multiplicity of entities: for instance, when one talks of the 'world' of a mathematician, 'world' signifies the realm of possible objects of mathematics.
- 3. "World" can be understood in another ontical sense—not, however, as those entities which Dasein essentially is not and which can be encountered within-the-world, but rather as the wherein a factical Dasein as such can be said to 'live'. "World" has here a pre-ontological existential signification. Here again there are different possibilities: "world" may stand for the 'public' we-world, or one's 'own' closest (domestic) environment.
- 4. Finally, "world" designates the ontologico-existential concept of worldhood. Worldhood itself may have as its modes whatever structural wholes any special 'worlds' may have at the time; but it embraces in itself the a priori character of worldhood in general.
Note, it is the third definition that Heidegger normally uses.
See also 
All citations referring to texts authored by Heidegger use "H.x" to refer to the original page number.
- Martin Heidegger, Being and Time, trans. John Macquarrie and Edward Robinson. New York: Harper & Row, 1962.
- Heidegger 1962, H.67–72
- Heidegger 1962, H.247
- Heidegger 1962, H.255
- Heidegger 1962, H.253-4
- Heidegger 1962, H.260–74
- Heidegger 1962, H.56
- Heidegger 1962, H.133
- Hubert Dreyfus, Being-in-the-World. Cambridge: MIT Press, 1995. p. 163
- Being and Time (1962), pg. 25
- Hubert Dreyfus and Charles Spinosa, "Further Reflections on Heidegger, Technology and the Everyday," in Nikolas Kompridis, ed. Philosophical Romanticism, New York: Routledge, 2006, 265.
- Nikolas Kompridis, "On World Disclosure: Heidegger, Habermas and Dewey," Thesis Eleven 1994; 37; 29-45.
- The Emergency of Being: On Heidegger's Contributions to Philosophy, p. 73
- Potentialities: Collected Essays, p. 117
- Martin Heidegger, Identity and Difference, trans. Joan Stambaugh. New York: Harper & Row, 1969.
- Heidegger, Martin (2010). Country Path Conversations. Translated by Bret W. Davis. Bloomington, Indiana: Indiana University Press. p. xi. ISBN 0-253-00439-X; ISBN 978-02-5300-439-0. "I have followed the established consensus in translating this term as 'releasement.' However, it should be kept in mind that the traditional and still commonly used German word conveys a sense of 'calm composure,' especially and originally that which accompanies an existential or religious experience of letting-go, being-let, and letting-be."
- Scott, Nathan A. (1969). Negative Capability. Studies in the New Literature and the Religious Situation. New Haven, Connecticut: Yale University Press. p. xiii. Cited in Dente, Carla; Soncini, Sara, eds. (2013). Shakespeare and Conflict. A European Perspective. Basingstoke: Palgrave Macmillan. Note 5. ISBN 1-137-14430-0; ISBN 978-11-3714-430-0.
- Heidegger, Martin (1959). Gelassenheit. Pfullingen: Neske. 13th Edition: Klett-Cotta (Stuttgart), 2004. ISBN 3-608-91059-X; ISBN 978-36-0891-059-9.
- Heidegger, Martin (2002). Aus der Erfahrung des Denkens: 1910-1976. Frankfurt: Vittorio Klostermann. p. 37. ISBN 3-465-03201-2; ISBN 978-34-6503-201-4.
- Hackett, Jeremiah, ed. (2012). A Companion to Meister Eckhart. Leiden: BRILL. p. 689. ISBN 9-004-18347-7; ISBN 978-90-0418-347-6.
- Heidegger, Martin. Country Path Conversations. Translated by Bret W. Davis. p. x.
- Dente, Carla; Soncini, Sara, eds. (2013). Shakespeare and Conflict. A European Perspective.
- Heidegger, Martin. Country Path Conversations. Translated by Bret W. Davis. p. xi. "The word Gelassenheit [...] has a long history in German thought. It was coined by Meister Eckhart in the thirteenth century and subsequently used by a number of other mystics, theologians, and philosophers."
- (Italian) See Carlo Angelino, Il religioso nel pensiero di Martin Heidegger, in Martin Heidegger, L'abbandono, tr. Adriano Fabris (Genova: Il Melangolo, 1986), p. 19.
- Michael Inwood, A Heidegger Dictionary, Malden, MA: Blackwell Publishers, 1999, ISBN 0-631-19195-3
- Heidegger 1962, H.64
- Roderick Munday, Glossary of Terms in Being and Time (March 2009)