Sein und Zeit

Author(s): Martin Heidegger · Year: 1927 (this edition 1967) · Type: book (an Abhandlung first published as Sonderdruck from Husserl's Jahrbuch für Philosophie und phänomenologische Forschung, Bd. VIII)

The foundational text of Heidegger's philosophical project: a treatise that aims to reawaken the question of the meaning of being (Seinsfrage) by way of an existential analytic of Dasein — the entity that we ourselves each are and for which its own being is at issue. The book proposes that Zeitlichkeit (temporality) is the ontological sense of Dasein's structural totality, Sorge (care), and that time (Temporalität) is the transcendental horizon of any understanding of being whatsoever. Of the originally projected two Parts (Part I: Die Interpretation des Daseins auf die Zeitlichkeit und die Explikation der Zeit als des transzendentalen Horizontes der Frage nach dem Sein; Part II: Grundzüge einer phänomenologischen Destruktion der Geschichte der Ontologie am Leitfaden der Problematik der Temporalität), only Part I's first two Sections were published; the third Section ("Zeit und Sein") and the whole of Part II were never written. The "Erste Hälfte" label was dropped from later editions because, as Heidegger states in the 1953 Vorbemerkung, "die zweite Hälfte läßt sich nach einem Vierteljahrhundert nicht mehr anschließen, ohne daß die erste neu dargestellt würde." Dedicated to Edmund Husserl in Verehrung und Freundschaft, Todtnauberg, 8 April 1926.

Core Arguments

Claim: The question of the meaning of being (Seinsfrage) has been forgotten since Plato and Aristotle and must be expressly repeated. Because: The three traditional dismissals — being is the most universal concept, undefinable, self-evident — are not refutations of the need to ask but symptoms of why it must be asked: universality is not generic but transcendental-analogical; undefinability follows from being's not-being-an-entity (and therefore demands a different kind of clarification rather than dispensing with it); the "self-evidence" only proves that we live within an a-priori Seinsverständnis (understanding of being) that has never been clarified. Against: scholastic-Aristotelian-Hegelian metaphysics that treats the question as settled or trivial; neo-Kantian epistemologies; positivistic dismissals of metaphysics. Location: §§ 1–2, H. 2–15.
Claim: Fundamentalontologie must be sought in the existenziale Analytik des Daseins — Dasein has a threefold priority (ontic, ontological, ontic-ontological) over all other entities. Because: Asking after the meaning of being requires fixing the Befragtes; every entity displays its being via some mode of access; the modes of access are themselves modes of being of the asker; the asker is therefore the entity that must be analyzed first. Dasein is ontically distinguished by the fact that its being is at issue for it — "Diesem Seienden geht es in seinem Sein um dieses Sein selbst" (§ 4, H. 12). Against: starting from theoretical reflection, from cogito sum (Descartes leaves the Seinssinn des sum indeterminate), from "consciousness" (Husserl's transcendental ego risks construing the constituting subject as a region of entities), or from "subject"/"person" (these inherit uncriticized antique ontology). Location: §§ 3–4, H. 8–15.
Claim: The history of ontology must be destroyed (Destruktion) — not annihilated but loosened in its sedimentation, returned to the originary experiences from which its categories grew. Destruktion has positive intent: it returns ontology to the phenomena that gave the basic concepts their Geburtsbrief. Because: Dasein is essentially historical; its understanding of being is taken over from a tradition that buries the sources from which it grew. Without Destruktion the inherited categories pass for self-evidence. The three intended stations of the Destruktion: (i) Kant's doctrine of schematism — where temporality almost broke through but was blocked by the uncriticized adoption of Descartes' position (§ 6); (ii) Descartes' cogito sum — which left sum ontologically indeterminate by transferring medieval ens creatum ontology onto the cogitating thing (§§ 19–21, § 6); (iii) the Greek determination of being as parousia/ousia — "presence" — which already involves a Zeitmodus (the present) without thematizing the temporal function it deploys (§ 6, H. 25–26). Against: doxographic and intellectual-historical treatments of the history of ontology that pass past positions for collectable "standpoints." Location: § 6, H. 19–27. (Part II of the projected book, which would have executed the Destruktion fully, was never written — only the Hegel-engagement at § 82 was published.)
Claim: Phenomenology is not a school or position but a methodological concept — to let what shows itself be seen from itself as it shows itself: ἀποφαίνεσθαι τὰ φαινόμενα (§ 7C, H. 34). Phenomenology of Dasein is Hermeneutik in the originary sense (interpretation), and Ontologie ist nur als Phänomenologie möglich (§ 7, H. 35). Because: λόγος as ἀποφαίνεσθαι means "to make manifest from the matter itself"; the structure of "showing-as" enables both truth (ἀλήθεια as uncovering) and falsehood (covering-over). The phenomenological Phänomen is the being of entities — that which precisely does not show itself first and foremost and so requires explicit thematization. Therefore ontology is only possible as phenomenology. Against: (i) phenomenology as a "school" or "position"; (ii) the construal of truth as correspondence (Aristotle's "judgment is true" has been catastrophically mis-Aristotelianized: ἀλήθεια is uncovering, with αἴσθησις and νοεῖν as more primordially "true" than assertion); (iii) the limitation of phenomenology to "consciousness." Location: § 7, H. 27–39.
Claim: In-der-Welt-sein is the unitary Grundverfassung of Dasein — not a composite of subject + world but a single existential structure with three structural moments (world, the Wer, the In-Sein). The first encounter with the world is with Zuhandenes (ready-to-hand equipment) in a Verweisungszusammenhang (referential totality), not with Vorhandenes (present-at-hand objects). Because: phenomenological description of practical engagement reveals that the hammer is not first encountered as a thing-with-properties to which usefulness is then added; the more it withdraws into competent use, the more authentically it is what it is (§ 15, H. 69). Worldhood is the Bedeutsamkeit (significance-structure) within which equipment is what it is. Vorhandenheit is a modification of, not a baseline beneath, Zuhandenheit; theoretical posture is a founded mode of engagement. Against: Cartesian dualism (res extensa + res cogitans, with "world" reduced to extended substance — §§ 19–21); empiricism's neutral sense-data substrate; any Wertphilosophie that adds value-predicates onto a value-neutral substrate. Location: §§ 12–18, H. 52–88.
Claim: The Wer of everyday Dasein is das Man — an existential structure, not a sociological mass-phenomenon. Mitsein is equiprimordial with In-der-Welt-sein; the everyday self is the Man-selbst, leveled-down by the structures of Abständigkeit, Durchschnittlichkeit, Einebnung, Öffentlichkeit, Seinsentlastung. "Das Man ist ein Existenzial und gehört als ursprüngliches Phänomen zur positiven Verfassung des Daseins" (§ 27, H. 129). Because: there is no neutral "subject" beneath the everyday self; the philosophical "I" is itself a posture taken up against a pre-given form of being-with. Empirical-sociological "ones" can be reductively explained only because they presuppose the existential structure that constitutes their possibility. Against: starting from the isolated ego; reading das Man as moral indictment of "the masses"; treating intersubjectivity as a problem ("first the self, then the other"). Location: §§ 25–27, H. 114–130.
Claim: The In-Sein itself has an equiprimordial threefold structure — Befindlichkeit (state-of-mind/attunement), Verstehen (understanding as projection of possibilities), Rede (discourse) — which together constitute the Erschlossenheit (disclosedness) of Dasein. In everydayness these degenerate into Gerede, Neugier, Zweideutigkeit — the structures of Verfallen (falling) into das Man. Because: Dasein is not first an intellect that adds an affective coloring; mood is itself a mode of disclosure. Understanding is the projective character of existence (Dasein is its possibilities). Discourse is the articulation of significance, of which assertion is a derivative theoretical mode. Verfallen is not a moral fall but the constitutive tendency of Dasein to interpret itself out of "the world." Against: the picture of cognition as basic mode with affect as secondary disturbance; reduction of language to assertion; theological-moralizing readings of inauthenticity. Location: §§ 28–38, H. 130–180.
Claim: Dasein's Strukturganzes is Sorge: "Sich-vorweg-schon-sein-in-(einer Welt-) als Sein-bei (innerweltlich begegnendem Seienden)" (§ 41, H. 192). Sorge is disclosed in the Grundbefindlichkeit of Angst (anxiety) — the mood in which world-as-significance falls away and Dasein faces itself as singular In-der-Welt-sein-können. Because: Angst — distinguished from Furcht (fear of a determinate entity) — suspends the everyday referential significance of the world and brings Dasein face-to-face with itself as the entity for whom its being is at issue. Angst is the methodological key to the wholeness of Dasein. The three "directions" of Sorge — Existenzialität (ahead-of), Faktizität (already-in), Verfallensein (being-alongside) — will be shown in Section 2 to correspond to the three temporal ekstases. Against: psychological reductions of anxiety; conflation of Angst with Furcht; readings of Sorge as moralized "worry" rather than ontological structure. Location: §§ 39–42, H. 180–212. (The Hyginus Cura fable at § 42 is invoked as a vorontological precursor.)
Claim: Realität (the being of Vorhandenes) is a derivative ontology; the "scandal of philosophy" (Kant) — that no proof of the external world has yet been given — is a sham scandal whose real scandal is that such a proof is demanded at all. Truth is primordially Erschlossenheit of Dasein (and only derivatively Übereinstimmung of judgment); ἀλήθεια is uncovering, with αἴσθησις and νοεῖν as more primordially "true" than assertion. "Sein ist das transcendens schlechthin" (§ 7C, H. 38). Because: Reality-as-Vorhandenheit presupposes In-der-Welt-sein; for something to be true as a proposition, the entity it speaks of must already be uncovered, which presupposes Dasein's disclosedness. Correspondence presupposes uncovering, not the reverse. Dasein is "in der Wahrheit" — and equiprimordially in der Unwahrheit. Against: Kant's "Refutation of Idealism" and the realism-idealism debate that frames it; veritas est adaequatio rei et intellectus; judgment-theories of truth. Location: §§ 43–44, H. 200–230.
Claim: The wholeness of Dasein is brought into view via Sein zum Tode (being-toward-death). Death is an existential: "der Tod als Ende des Daseins ist die eigenste, unbezügliche, gewisse und als solche unbestimmte, unüberholbare Möglichkeit des Daseins" (§ 52, H. 258–259). Authentic being-toward-death is Vorlaufen — running ahead into the possibility as a possibility, not its actualization. Because: to grasp Dasein whole the "missing-end" must be thinkable without destroying the entity. The other's death cannot stand in for one's own because death is jemeinig (in-each-case-mine). Vulgar "one dies" is the Verdeckung of death-as-mine — das Man averaging away the existential structure. Vorlaufen "ermöglicht allererst diese Möglichkeit und macht sie als solche frei" (§ 53, H. 263). Against: biological, sociological, theological accounts of death; Epicurean dismissals; readings of authentic Sein zum Tode as a death-cult or moral prescription. Location: §§ 46–53, H. 235–267.
Claim: Authentic Seinkönnen is attested existentielly in Gewissen (conscience) — the silent call of care to itself, summoning Dasein out of lostness-in-das-Man to its ownmost possibility — disclosing Schuldigsein (being-guilty) as the Nichtigkeit of Dasein (the null ground of its own thrown possibilities). The proper response is Entschlossenheit (resoluteness), not voluntarist self-assertion but lucid taking-over of one's thrown possibilities. Because: without existentielle attestation the analysis of authentic Seinkönnen would remain a constructed possibility. Conscience supplies the attestation: phenomenologically, the call does occur, and an existential analysis reveals its call-structure. Location: §§ 54–60, H. 267–301.
Claim: Zeitlichkeit (temporality) is the ontological sense of Sorge. The unity of Existenzialität, Faktizität, Verfallensein is grounded in the unity of three Ekstasen — Zukunft (future), Gewesenheit (having-been), Gegenwart (present) — that temporalize themselves (Zeitlichkeit zeitigt sich). Originary temporality is finite — its primary ekstasis is the future, futural precisely because grasped vom Tode her. Because: Sorge has three irreducible moments; each grounds in a temporal ekstasis; the unity of care therefore is the unity of temporal ekstases. The "now-sequence" conception of time (one moment after another, infinite, stretched between past and future) is a derivative — it stems from a vulgarization of Zeitlichkeit via the temporalization of Vorhandenheit. "Zeitlichkeit ist das ursprüngliche 'Außer-sich' an und für sich selbst" (§ 65, H. 329). Against: Aristotle's definition of time (ἀριθμὸς κινήσεως κατὰ τὸ πρότερον καὶ ὕστερον) — the carrier of the entire metaphysical tradition; Newtonian-Kantian absolute time; Bergson (Heidegger says: Bergson has the symptom right but the diagnosis wrong — vulgar time is not space but a derivative of Zeitlichkeit); Hegel's identification of time as the angeschaute Negativität of the Geist, the most extensive engagement at § 82. Location: §§ 61–66, H. 301–334.
Claim: Dasein is constitutively historical: Geschichtlichkeit is the Geschehen (happening) of Dasein itself; Schicksal (fate) and Geschick (destiny) are existential moments of historicity, the latter as the historical-collective Geschehen of a Generation. Wiederholung (repetition) is the mode in which a possibility from one's Erbe (heritage) is owned as one's own. "Das eigentliche Sein zum Tode, das heißt die Endlichkeit der Zeitlichkeit, ist der verborgene Grund der Geschichtlichkeit des Daseins" (§ 74, H. 386). Because: Dasein is constitutively futural-having-been; inheritance is not contingent influence but the way Dasein has its possibilities. Historiography (Historie) is grounded in the Geschichtlichkeit of the inquirer. World-history (Weltgeschichte) is a derivative of Dasein's historicity, not the converse. Against: Lebensphilosophie-without-existential-analysis (Dilthey/Yorck honored as precursors but criticized at § 77); historicism's relativism; the picture of history as a chronicle of events external to its subject. Location: §§ 72–77, H. 372–404.
Claim (closing aporia): Whether Zeit itself is the Horizont des Seins — whether the Zeitlichkeit of Dasein opens out into the Temporalität of Being itself — remains unanswered at the close of the published portion. The book ends with two questions: "Führt ein Weg von der ursprünglichen Zeit zum Sinn des Seins? Offenbart sich die Zeit selbst als Horizont des Seins?" (§ 83, H. 437). This is the seam at which the unwritten third Abschnitt ("Zeit und Sein") was to begin. Because: the analysis carries through to its limit — all structures of Dasein are interpretable as modes of Zeitlichkeit. But to move from Zeitlichkeit-of-Dasein to Temporalität-of-Sein requires a turn that S&Z does not accomplish; the Kehre in Heidegger's later thought is in part the attempt to traverse what S&Z's third Abschnitt was to have done. Against: readings of S&Z as a completed system in which Dasein is the foundation of being. Location: § 83, H. 436–437.

Argumentative Movement

S&Z proceeds by phenomenological description and existential interpretation, not by premise-conclusion deduction. The movement is: (i) prepare the question (Einleitung) by exhibiting the necessity of the Seinsfrage and choosing Dasein as the Befragtes; (ii) characterize Dasein in its average everydayness (Erster Abschnitt) — In-der-Welt-sein, Mitsein + das Man, Befindlichkeit-Verstehen-Rede, Verfallen, Sorge, truth as Erschlossenheit; (iii) deepen the analysis from average everydayness to Dasein-as-whole (Zweiter Abschnitt) — Sein zum Tode, Gewissen, vorlaufende Entschlossenheit, Zeitlichkeit as the sense of Sorge, the temporal interpretation of everydayness, Geschichtlichkeit, Innerzeitigkeit vs. originary time; (iv) close with the aporia that opens out toward the unwritten third Abschnitt. The method is hermeneutic-phenomenological: the analysis circles back on itself, deepening at each pass.

Key Findings

Sein ist nicht so etwas wie Seiendes (§ 2): the ontological difference, operative throughout though not named as Differenz until later writings.
Sein ist je das Sein eines Seienden (§ 2): being is always being-of-an-entity; no Platonic eidos of being separable from its instances.
Die »Allgemeinheit« des Seins »übersteigt« alle gattungsmäßige Allgemeinheit (§ 1): being is transcendens, not genus.
Das »Wesen« des Daseins liegt in seiner Existenz (§ 9): Dasein's essence is its existence; Existenzialien (existentials) are distinct from Kategorien (categories) which apply to non-Dasein entities. The Existenzial / Kategorial distinction is the silent organizing principle of the entire analytic.
Zuhandenheit ist die ontologisch-kategoriale Bestimmung von Seiendem, wie es »an sich« ist (§ 15): the An-sich of equipment is its readiness-to-hand, not its bare presence.
Das Wovor der Angst ist das In-der-Welt-sein als solches (§ 40): Angst discloses the world as world.
Das Dasein ist seine Erschlossenheit (§ 28): Dasein is its disclosedness — the Lichtung-image already in S&Z. "Es ist 'erleuchtet', besagt: an ihm selbst als In-der-Welt-sein gelichtet, nicht durch ein anderes Seiendes, sondern so, daß es selbst die Lichtung ist" (H. 133).
Sein ist das transcendens schlechthin. ... Phänomenologische Wahrheit (Erschlossenheit von Sein) ist veritas transcendentalis (§ 7C, H. 38).
Zeitlichkeit ist das ursprüngliche »Außer-sich« an und für sich selbst (§ 65): originary temporality is ekstatic.
The three Ekstasen of Zeitlichkeit — Zukunft, Gewesenheit, Gegenwart — temporalize themselves, with Zukunft having primacy.
Originary temporality is finite; the vulgar concept of time (infinite now-sequence) is its leveled-down derivative.

Methodology

Hermeneutic phenomenology, in the originary sense of ἑρμηνεύειν: interpretation that articulates the pre-thematic Seinsverständnis belonging to Dasein. The method has three methodological pillars: (i) the Vorbegriff der Phänomenologie (§ 7) — ἀποφαίνεσθαι τὰ φαινόμενα; (ii) the Destruktion of inherited ontology (§ 6) — loosening the sedimented categories of antiquity, medieval scholasticism, and modernity to recover their originary phenomena; (iii) the hermeneutic circle (§ 32) — interpretation is Vorhabe-Vorsicht-Vorgriff (fore-having / fore-sight / fore-grasp), and circularity is benign because Dasein's pre-ontological understanding of being already operates whenever it asks the Seinsfrage. The unity of the three: phenomenology must be hermeneutic because the phenomenon to be uncovered (being) is precisely what does not show itself first; Destruktion is the method by which inherited interpretive sediments are made transparent.

Concepts Developed

S&Z is the primary (originating) source for the following concept entries:

dasein — the entity that we ourselves each are, for which its being is at issue; not "human being" but a reiner Seinsausdruck.
sorge — the Strukturganzes of Dasein: Sich-vorweg-schon-sein-in-(einer Welt-) als Sein-bei.
zeitlichkeit — originary ekstatic temporality as the ontological sense of Sorge; distinct from MP's corporeal-perceptual temporality and from the Temporalität of being itself.
sein-zum-tode — being-toward-death as eigenste, unbezügliche, gewisse und unbestimmte, unüberholbare Möglichkeit; authentic mode is Vorlaufen.
das-man — the Wer of everyday Dasein as an existential structure (not a sociological aggregate); Abständigkeit, Durchschnittlichkeit, Einebnung, Öffentlichkeit, Seinsentlastung.
In-der-Welt-sein as the Heideggerian concept distinct from MP's être au monde — see being-in-and-toward-the-world for the MP version and the cross-reference within that page.

S&Z is also the originating ground for ontological-difference (operative throughout, the terminus technicus "Differenz" arrives in the 1930s+), aletheia as Erschlossenheit/Unverborgenheit in the 1927 register, lichtung (operative at § 28 — Dasein als die Lichtung — long before the 1964 Lichtung-essay), and the task-of-thinking (the 1927 task is the Destruktion of inherited ontology and the Ausarbeitung der Seinsfrage; the 1964 essay renames this task).

Concepts Referenced

ereignis — not a Heideggerian terminus technicus in S&Z; the term arrives in the 1930s onward (Beiträge, etc.). S&Z's analogue is the Zeitigung of Zeitlichkeit.
lebenswelt — Husserl's term arrives in the mid-1930s; S&Z works with Umwelt and In-der-Welt-sein. The wiki's lebenswelt page predates this and is anchored elsewhere.
Begriff, Vernunft, Geist, Subjekt, Bewußtsein, Person — all named as terms whose Seinssinn S&Z aims to recover (§ 10).
silence — Schweigen appears at § 34 as a positive mode of Rede, not its absence. (A cross-tradition resonance with MP's parole parlante / parole parlée — see Connections below.)

Terminology

Key technical terms (German | working English | location of locus classicus):

German	English	Locus
Sein	being	passim
Seiendes	entity / being-as-individual	passim
Dasein	"Da-sein" (the being-there for which being is at issue)	§ 4, § 9
Existenz	existence (Dasein's mode of being)	§ 9
Existenzial(ien)	existentials (categories of Dasein)	§ 9
Kategorie(n)	categories (of non-Dasein entities)	§ 9
Existenziell	ontic comportment toward one's existence	§ 4
Existenzial	ontological-structural analysis of existence	§ 4
Vorhandenheit	presence-at-hand	§§ 9, 15, 21
Zuhandenheit	readiness-to-hand	§ 15
Zeug	equipment	§ 15
Bewandtnis	involvement	§ 18
Bedeutsamkeit	significance(-structure)	§ 18
Verweisung	reference (in the equipmental sense)	§§ 17–18
Worumwillen	for-the-sake-of-which (terminating in Dasein)	§ 18
Um-zu	in-order-to	§ 18
In-der-Welt-sein	being-in-the-world	§§ 12–13
Umwelt	environing-world	§ 14 ff.
Mitsein, Mitdasein	being-with, Dasein-with	§§ 25–26
das Man	the they / the one (existential structure)	§ 27
Erschlossenheit	disclosedness	§ 28
Befindlichkeit	state-of-mind / attunement	§ 29
Stimmung	mood	§ 29
Verstehen	understanding	§ 31
Entwurf	projection	§ 31
Auslegung	interpretation	§ 32
Vorhabe / Vorsicht / Vorgriff	fore-having / fore-sight / fore-grasp	§ 32
Aussage	assertion	§ 33
Rede	discourse	§ 34
Schweigen	silence (as positive mode of Rede)	§ 34
Gerede, Neugier, Zweideutigkeit	idle talk, curiosity, ambiguity	§§ 35–37
Verfallen	falling	§ 38
Geworfenheit	thrownness	§§ 29, 38
Sorge	care (Dasein's structural totality)	§ 41
Angst	anxiety (the Grundbefindlichkeit)	§ 40
Furcht	fear (of a determinate entity)	§ 30
Sein zum Tode	being-toward-death	§§ 46–53
Jemeinigkeit	in-each-case-mineness	§ 9
Eigentlichkeit / Uneigentlichkeit	authenticity / inauthenticity	passim
Gewissen	conscience	§§ 54–60
Schuldigsein	being-guilty	§ 58
Entschlossenheit	resoluteness	§ 60
Vorlaufende Entschlossenheit	anticipatory resoluteness	§§ 62, 65
Zeitlichkeit	temporality (of Dasein)	§ 65
Temporalität	Temporality (of Being itself — projected goal of unwritten Section 3)	§ 5, § 83
Ekstasen	ekstases (of temporality)	§ 65
Zukunft, Gewesenheit, Gegenwart	future, having-been, present	§ 65
Geschichtlichkeit	historicity	§ 74
Wiederholung	repetition / retrieval	§ 74
Erbe, Schicksal, Geschick	heritage, fate, destiny	§ 74
Innerzeitigkeit	within-time-ness	§ 78
Destruktion	destruction / dismantling (of history of ontology)	§ 6
Phänomenologie	phenomenology	§ 7
Aletheia / Unverborgenheit	unconcealment	§ 7B, § 44
Lichtung	clearing	§ 28
veritas transcendentalis	phenomenological truth	§ 7C

Key Passages

"Die genannte Frage ist heute in Vergessenheit gekommen, obwohl unsere Zeit sich als Fortschritt anrechnet, die »Metaphysik« wieder zu bejahen." (§ 1, H. 2)

"Der Begriff des »Seins« ist vielmehr der dunkelste." (§ 1, H. 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." (§ 4, H. 12)

"Daher muß die Fundamentalontologie, aus der alle andern erst entspringen können, in der existenzialen Analytik des Daseins gesucht werden." (§ 4, H. 13)

"Diese Aufgabe verstehen wir als die am Leitfaden der Seinsfrage sich vollziehende Destruktion des überlieferten Bestandes der antiken Ontologie auf die ursprünglichen Erfahrungen, in denen die ersten und fortan leitenden Bestimmungen des Seins gewonnen wurden." (§ 6, H. 22)

"Seiendes ist in seinem Sein als »Anwesenheit« gefaßt, d. h. es ist mit Rücksicht auf einen bestimmten Zeitmodus, die »Gegenwart«, verstanden." (§ 6, H. 25)

"Ontologie ist nur als Phänomenologie möglich." (§ 7, H. 35)

"Sein ist das transcendens schlechthin. Die Transzendenz des Seins des Daseins ist eine ausgezeichnete, sofern in ihr die Möglichkeit und Notwendigkeit der radikalsten Individuation liegt. ... Phänomenologische Wahrheit (Erschlossenheit von Sein) ist veritas transcendentalis." (§ 7C, H. 38)

"Das »Wesen« des Daseins liegt in seiner Existenz." (§ 9, H. 42)

"Zuhandenheit ist die ontologisch-kategoriale Bestimmung von Seiendem, wie es »an sich« ist." (§ 15, H. 71)

"Das Man ist ein Existenzial und gehört als ursprüngliches Phänomen zur positiven Verfassung des Daseins." (§ 27, H. 129)

"Es ist »erleuchtet«, besagt: an ihm selbst als In-der-Welt-sein gelichtet, nicht durch ein anderes Seiendes, sondern so, daß es selbst die Lichtung ist. ... Das Dasein ist seine Erschlossenheit." (§ 28, H. 133)

"Das Wovor der Angst ist das In-der-Welt-sein selbst." (§ 40, H. 187)

"Das Sein des Daseins besagt: Sich-vorweg-schon-sein-in-(der-Welt-) als Sein-bei (innerweltlich begegnendem Seienden). Dieses Sein erfüllt die Bedeutung des Titels Sorge." (§ 41, H. 192)

"Der Tod als Ende des Daseins ist die eigenste, unbezügliche, gewisse und als solche unbestimmte, unüberholbare Möglichkeit des Daseins." (§ 52, H. 258–259)

"Das Sein zum Tode als Vorlaufen in die Möglichkeit ermöglicht allererst diese Möglichkeit und macht sie als solche frei." (§ 53, H. 263)

"Zeitlichkeit enthüllt sich als der Sinn der eigentlichen Sorge. ... Zeitlichkeit ist das ursprüngliche »Außer-sich« an und für sich selbst." (§ 65, H. 326, 329)

"Nur eigentliche Zeitlichkeit, die zugleich endlich ist, macht so etwas wie Schicksal, das heißt eigentliche Geschichtlichkeit möglich." (§ 74, H. 385)

"Das eigentliche Sein zum Tode, das heißt die Endlichkeit der Zeitlichkeit, ist der verborgene Grund der Geschichtlichkeit des Daseins." (§ 74, H. 386)

"Der »Geist« fällt nicht erst in die Zeit, sondern existiert als ursprüngliche Zeitigung der Zeitlichkeit." (§ 82, H. 435)

"Führt ein Weg von der ursprünglichen Zeit zum Sinn des Seins? Offenbart sich die Zeit selbst als Horizont des Seins?" (§ 83, H. 437 — the book's closing two questions, into which the unwritten third Abschnitt "Zeit und Sein" was to step)

What's Not Obvious

Three things about S&Z that would not appear in a conventional summary:

S&Z is unfinished by design as much as by circumstance. The 1953 Vorbemerkung admits that the second half could not be appended after a quarter-century without rewriting the first. But the published Erster Teil also lacks its own third Abschnitt ("Zeit und Sein"), and the book ends on two questions — "Führt ein Weg von der ursprünglichen Zeit zum Sinn des Seins? Offenbart sich die Zeit selbst als Horizont des Seins?" (§ 83, H. 437). The closing aporia is the seam at which the Kehre in Heidegger's later thought attempts to traverse what the published text could not, approaching the question from Sein/Ereignis toward Dasein rather than from Dasein toward Being. The wiki's ontological-difference §"1964 Marginal Reframe" already documents one node of this trajectory: the 1964 Handexemplar marginal at GA 14 p. 87 reframes the SuZ-Seinsfrage as "der verkürzte Titel für die Frage nach der Herkunft der ontologischen Differenz" — and the Herkunft is what § 83 leaves open.
The Lichtung-image is already operative in 1927. Standard readings periodize Heidegger sharply across the Kehre and locate Lichtung in the post-1930s work. But § 28 (H. 133) describes Dasein's Erschlossenheit in unmistakable Lichtung-language: "Es ist »erleuchtet«, besagt: an ihm selbst als In-der-Welt-sein gelichtet, nicht durch ein anderes Seiendes, sondern so, daß es selbst die Lichtung ist." The continuity matters because the 1964 essay's renamed task — "Lichtung und Anwesenheit" — is not a new concept but a re-grounding of the 1927 figure: the post-Kehre Lichtung is the Lichtung-of-the-Anwesenheit-of-Being, no longer tied to Dasein's Erschlossenheit as 1927 had it. The wiki's lichtung should anchor this development from 1927-Lichtung-of-Dasein to 1964-Lichtung-of-Anwesenheit; see Connections below.
§ 82's Hegel-engagement is the only published station of the projected Destruktion. Part II — the entire Destruktion-of-the-history-of-ontology program — was never written. The only published "station" is the engagement with Hegel's identification of time as the angeschaute Negativität of the Geist (§ 82). The footnote at H. 432 reads: "Es läßt sich zeigen, daß Hegels Zeitbegriff sogar direkt aus der »Physik« des Aristoteles geschöpft ist." Heidegger reads Hegel as the most extreme nivellierung of the Aristotelian now-sequence, with the Hegel-Aristotle filiation as a future konkrete vergleichende philosophische Interpretation. Bergson's Essai on durée (which Bergson companion-published with a dissertation Quid Aristoteles de loco senserit) is footnoted in the same passage as another extension of the same Aristotelian inheritance: H. takes Bergson to be reacting against this inheritance but still operating within it. § 82 is therefore both the only delivered Destruktion-station and a sketch for an unwritten history of metaphysics-as-temporal-derivative.

Critique / Limitations

Part II never written. The Destruktion was outlined in § 6 — Kant's schematism, Descartes' cogito sum, the Greek parousia/ousia — but executed only in § 82's Hegel-engagement and partially across § 6, § 19–21 (Descartes), and § 44 (truth). The book's epigram-status promise is not delivered.
Section 3 ("Zeit und Sein") never written. The transition from Zeitlichkeit-of-Dasein to Temporalität-of-Being is signposted but not traversed. Heidegger's 1962 lecture "Zeit und Sein" partly returns to the gap.
The Geschichtlichkeit-section's vocabulary — Schicksal/Geschick/Generation — has notoriously fraught resonances, prepared for the political entanglements of 1933-34 (without S&Z entailing them). The wiki's heidegger-as-silenced-interlocutor notes that the Lefort-edited In Praise of Philosophy implicitly distances MP from precisely this Heideggerian register.
The Husserl-relation is asymmetric in the text. The dedication is to Husserl in Verehrung und Freundschaft; the methodological remarks (§ 7) credit phenomenology to Husserl. But the central move — bypassing the constituting-consciousness model in favor of the analytic of Dasein — is precisely against Husserl's transcendental subject, without being argued against him by name.
Hermeneutic-circle benignness is asserted rather than demonstrated. § 32 says the circle is not vicious because Dasein's pre-ontological Seinsverständnis already operates; but whether this Verständnis is neutral enough to deliver a non-contaminated interpretation is not shown.
The Existenzial / Kategorial distinction is introduced terminologically (§ 9) without sustained argument; the book then deploys it as foundational. Critics (Tugendhat among them) have pressed this.

Connections

is the foundational text developed by Martin Heidegger — the locus classicus for Dasein, Sorge, Zeitlichkeit, Sein zum Tode, das Man, In-der-Welt-sein, Erschlossenheit, Verfallen, and the Destruktion-program.
is dedicated to Edmund Husserl in Verehrung und Freundschaft (8 April 1926). Husserl's Logische Untersuchungen is credited at § 7 as the breakthrough that makes phenomenological investigation possible; the dedication marks the inheritance even as the book's central move (analytic of Dasein in place of constituting consciousness) takes a path Husserl would later, in Krisis (1936) and the Ideen II MS, find unacceptable.
engages adversarially with Parmenides, Plato, Aristotle, Hegel — but the Destruktion of this lineage was projected for the unwritten Part II.
is the silent target of the Cartesian cogito sum — see §§ 6, 10, 43; the cogito sum leaves the Seinssinn des sum indeterminate.
is implicitly read by Kant as the most-advanced-and-still-not-far-enough station — Kant's schematism almost reaches temporality but is blocked by the uncriticized adoption of Cartesian position (§ 6).
contrasts with merleau-ponty-1945-phenomenology-of-perception on the central existential structure — Heidegger's In-der-Welt-sein is articulated through Zeug-handling and das Man; MP's être au monde is articulated through corporeal-perceptual engagement (see being-in-and-toward-the-world). Both proceed by reformulating the Cartesian starting point but differ on whether the body or interpretation is the basic axis of being-in-the-world. The MP-Heidegger relation is archivally thinner than secondary literature typically asserts: see claims#mp-heidegger-reception-archivally-thin (supported). MP's personal copy of S&Z is underlined only at §§ 1–14 and §§ 25–27 — exactly the sections on the Seinsfrage, Dasein-analytic foundations, Mitsein and das Man.
is the text whose final aporia (§ 83) is approached from the other side by heidegger-1964-end-of-philosophy — see ontological-difference §"1964 Marginal Reframe" and lichtung §"Lichtung as the Renamed Title of the SuZ-Task." The 1964 essay marginalia explicitly reframe the SuZ-Seinsfrage as "der verkürzte Titel für die Frage nach der Herkunft der ontologischen Differenz."
develops the framework whose continuation is heidegger-1961-nietzsche-i and heidegger-1961-nietzsche-ii — the Nietzsche lectures (1936-46) and the 1964 essay are unintelligible without S&Z's Seinsfrage-program. Heidegger's 1961 Vorwort to Nietzsche I explicitly frames the publication as making visible "the Denkweg I traveled from 1930 to the Brief über den Humanismus."
shares mechanism with merleau-ponty-2022-possibility-of-philosophy on the question of indirect access to Being — both refuse direct ontology, though they refuse for different reasons (Heidegger: because Being withdraws as it gives itself in beings; MP: because the body's pre-objective opening is itself the only access). The mechanism shared is the via negativa via Verbergung / Schein / Verstellung (Heidegger) / invisible / latency / écart (MP).
is engaged adversarially by chouraqui-2014-ambiguity-and-absolute on the question of metaphysics and subjectivity — see martin-heidegger §"Chouraqui's Critique" for the full argument; Chouraqui's quarrel is with the Nietzsche-lectures rather than with S&Z directly, but the underlying issue (Heidegger's framing of metaphysics as a forgetting-of-Being) originates here.

Sources

(No incoming source citations — this is a primary source. The page is itself the origin anchor for the concepts listed under Concepts Developed.)