Martin Heidegger (September 26, 1889 – May 26, 1976) (pronounced ) was a highly influential German philosopher. His best known work is Being and Time (1927).

Heidegger claimed that Western philosophy has, since Plato, misunderstood what it means for something to be, tending to approach this question in terms of a being, rather than asking about being itself. In other words, Heidegger believed all investigations of being have historically focused on particular entities and their properties, or have treated being itself as an entity, or substance, with properties. A more authentic analytic of being would, for Heidegger, investigate "that on the basis of which beings are already understood," or that which underlies all particular entities and allows them to show up as entities in the first place. But since philosophers and scientists have overlooked the more basic, pre-theoretical ways of being from which their theories derive, and since they have incorrectly applied those theories universally, they have confused our understanding of being. To avoid these deep-rooted misconceptions, Heidegger believed philosophical inquiry must be conducted in a new way, through a process of retracing the steps of the history of philosophy.

Heidegger argues that Plato's fallacies resulted in two evolving but contradictory schools of thought, most readily observed during the Age of Reason as the division between British empiricism and German idealism, but traceable to every stage of Western thought. All that we understand, from the way we speak to our notions of "common sense," is susceptible to error, because it has evolved from Plato's fundamental mistakes about the nature of being. These mistakes filter into the terms through which being is articulated in the history of philosophy—reality, logic, God, consciousness, the present, et cetera. In his later philosophy, Heidegger argues that these errors have profoundly affected the way in which human beings relate to modern technology.

Philosophers are divided in their opinion of Heidegger: some regard him as the greatest philosopher of the 20th century, while others view his writing as bombastic nonsense. Nonetheless, his work has exercised a deep influence on philosophy, theology and the humanities, being key to the development of existentialism, hermeneutics, deconstruction, postmodernism, and continental philosophy in general. Heidegger's thought directly informs the works of major philosophers such as Karl Jaspers, Leo Strauss, Hans-Georg Gadamer, Jean-Paul Sartre, Emmanuel Lévinas, Hannah Arendt, Maurice Merleau-Ponty, Michel Foucault, and Jacques Derrida.

Heidegger infamously supported National Socialism. This has provoked fierce debate among and between supporters and detractors: some see it as a personal folly largely irrelevant to his philosophy, while others think it reveals flaws inherent in his thought.

Heidegger was born in rural Meßkirch, Germany. Raised a Roman Catholic, he was the son of the sexton of the village church. His family could not afford to send him to university, so he entered a Jesuit seminary. After studying theology at the University of Freiburg from 1909 to 1911, he switched to philosophy. Heidegger completed his doctoral thesis on psychologism in 1914, and in 1916 finished his venia legendi with a thesis on Duns Scotus. In the two years following, he worked first as an unsalaried Privatdozent, then served as a soldier during the final year of World War I, working behind a desk and never leaving Germany. After the war, he served as a salaried senior assistant to Edmund Husserl at the University of Freiburg until 1923.

In 1923, he was elected to an extraordinary Professorship in Philosophy at the equally reputable but very Protestant University of Marburg. At Marburg his colleagues included Rudolf Bultmann, Ernst Friedländer, Nicolai Hartmann, and Paul Natorp. His students included Hans-Georg Gadamer, Hannah Arendt, Karl Löwith, Gerhard Krüger, Leo Strauss, Günther Anders, and Hans Jonas.

When Husserl retired in 1928, Heidegger accepted Freiburg's election to be his successor, in spite of a counter-offer by Marburg. Heidegger remained at Freiburg for the rest of his life, declining a number of later offers including one from Berlin, the most prestigious German university of the day. Among his students at Freiburg were Herbert Marcuse and Ernst Nolte.

In 1933, after Hitler's rise to power, Heidegger was elected Rector of the University of Freiburg and he subsequently joined the Nazi party. Heidegger's inaugural address, the Rektoratsrede, became notorious. His tenure was, however, unsuccessful, and he resigned his position in 1934 (though he retained his party membership until the end of the war).

After the war, Heidegger was forbidden by the French Occupation Authority from teaching in Germany, but this decision was rescinded in 1951, when he became Professor emeritus with all privileges. He then taught regularly from 1951 until 1958, and by invitation until 1967.

A more detailed account of the personal and philosophical relations between Heidegger and National Socialism is given below.

In 1917, Heidegger married Elfriede Petri on March 21 in a Catholic ceremony officiated by his friend Engelbert Krebs and a week later in a Protestant ceremony in the presence of her parents. Their first son Jörg was born in 1919. According to the recently published correspondence between the spouses, Hermann (born 1920) is the son of Elfriede and Friedel Caesar. Martin Heidegger had extramarital affairs with Hannah Arendt and Elisabeth Blochmann, both students of Heidegger and both Jewish. He helped the latter emigrate from Germany prior to World War II and resumed contact with both of them after the war. Heidegger spent a good deal of his life at a somewhat isolated mountain hut at Todtnauberg, on the edge of the Black Forest. He considered the seclusion provided by the forest to be the best environment in which to engage in philosophical thought.

Heidegger died on May 26, 1976 and was buried in the Meßkirch cemetery.

Heidegger’s philosophy is essentially an attempt to marry two insights.

*The first of these is Heidegger’s insight that, in the course of over two thousand years of history, philosophy has attended to all the beings that can be found in the world (including the “world” itself), but has forgotten to ask what “being” itself is. This is Heidegger’s “question of being,” and it is Heidegger’s fundamental concern throughout his work from the beginning of his career until its end. One crucial source of this insight was Heidegger’s reading of Franz Brentano’s treatise on Aristotle’s manifold uses of the word “being,” a work which provoked Heidegger to ask what kind of unity underlies this multiplicity of uses. Heidegger opens his magnum opus, Being and Time, with a citation from Plato’s Sophist indicating that Western philosophy has neglected being because it was considered obvious, rather than as worthy of question. Heidegger’s intuition about the question of being is thus an historical argument, which in his later work becomes his concern with the “history of being,” that is, the history of the forgetting of being, which according to Heidegger requires that philosophy retrace its footsteps through a productive “destruction” of the history of philosophy. *The second intuition animating Heidegger’s philosophy derives from the influence of Edmund Husserl, a philosopher largely uninterested in questions of philosophical history. Rather, Husserl argued that all that philosophy could and should be is a description of experience (hence the phenomenological slogan, “to the things themselves”). But for Heidegger, this meant understanding that experience is always already situated in a world and in ways of being. Thus Husserl's understanding that all consciousness is "intentional" (in the sense that it is always intended toward something, and is always "about" something; intentionality has been called the "aboutness" of things) is transformed in Heidegger's philosophy, becoming the thought that all experience is grounded in "care." This is the basis of Heidegger’s “existential analytic,” as he develops it in Being and Time. Heidegger argues that to be able to describe experience properly means finding the being for whom such a description might matter. Heidegger thus conducts his description of experience with reference to “Dasein," the being for whom being is a question. In Being and Time, Heidegger criticized the abstract and metaphysical character of traditional ways of grasping human existence as rational animal, person, man, soul, spirit, or subject. Dasein, then, is not intended as a way of conducting a "philosophical anthropology," but is rather understood by Heidegger to be the condition of possibility for anything like a "philosophical anthropology." In the course of his existential analytic, Heidegger argues that Dasein, who finds itself thrown into the world amidst things and with others, is thrown into its possibilities, including the possibility and inevitability of one’s own mortality. The need for Dasein to assume these possibilities, that is, the need to be responsible for one’s own existence, is the basis of Heidegger’s notions of authenticity and resoluteness—that is, of those specific possibilities for Dasein which depend on escaping the “vulgar” temporality of calculation and of public life.

The marriage of these two insights depends on the fact that each of them is essentially concerned with time. That Dasein is thrown into an already existing world and thus into its mortal possibilities does not only mean that Dasein is an essentially temporal being; it also implies that the description of Dasein can only be carried out in terms inherited from the Western tradition itself. For Heidegger, unlike for Husserl, philosophical terminology could not be divorced from the history of the use of that terminology, and thus genuine philosophy could not avoid confronting questions of language and meaning. The existential analytic of Being and Time was thus always only a first step in Heidegger’s philosophy, to be followed by the “destruction” of the history of philosophy, that is, a transformation of its language and meaning, that would have made of the existential analytic only a kind of “limit case” (in the sense in which special relativity is a limit case of general relativity).

That Heidegger did not write this second part of Being and Time, and that the existential analytic was left behind in the course of Heidegger’s subsequent writings on the history of being, might be interpreted as a failure to conjugate his account of individual experience with his account of the vicissitudes of the collective human adventure that he understands the Western philosophical tradition to be. And this would in turn raise the question of whether this failure is due to a flaw in Heidegger’s account of temporality, that is, of whether Heidegger was correct to oppose vulgar and authentic time.

Being and Time (German title: Sein und Zeit), published in 1927, is considered by many to be Heidegger's most important work. This epochal book was his first significant academic work, and earned him a professorship at Freiburg University. It investigates the question of being by asking about the being for whom being is a question. Heidegger names this being Dasein (see above), and the book pursues its investigation through themes such as mortality, anxiety, temporality, and historicity. It was Heidegger's original intention to write a second half of the book, consisting in a "Destruktion" of the history of philosophy—that is, the transformation of philosophy by re-tracing its history—but he never completed this project.

Being and Time influenced many thinkers, including existentialist thinkers like Jean-Paul Sartre (although Heidegger distanced himself from existentialism—see below).

Some have argued that Heidegger's thought after Being and Time exhibits a "turn" in his thinking (die Kehre). Heidegger denied this in a letter—published by William J. Richardson in Heidegger: Through Phenomenology to Thought (1963)—which stated that, if there had been a turn at all, it was simply a matter of going deeper into the same matters. In his later work, Heidegger largely abandons the account of Dasein as a pragmatic, engaged, worldly agent, and instead discusses other elements necessary to an understanding of being, notably language, the earth (as the almost ineffable foundation of world) and the presence of the gods. Nevertheless, Dasein (or "mortals," as he later prefers to say) remains a crucial part of the coming-about or event (Ereignis) of being.

In his later works, Heidegger turns from "doing" to "dwelling." He focuses less on the way in which the structures of being are revealed in everyday behavior and in the experience of Angst, and more on the way in which behavior itself depends on a prior "openness to being." The essence of being human is the maintenance of this openness. Heidegger contrasts this openness to the "will to power" of the modern human subject, who subordinates beings to his own ends.

Heidegger understands the commencement of the history of Western philosophy as a brief period of authentic openness to being, during the time of the pre-Socratics, especially Parmenides, Heraclitus, and Anaximander. This was followed, according to Heidegger, by a long period increasingly dominated by the forgetting of this initial openness, a period which commences with Plato.

Two recurring themes of Heidegger's later writings are poetry and technology. Heidegger sees poetry as a pre-eminent way in which beings are revealed "in their being." The play of poetic language (which is, for Heidegger, the essence of language itself) reveals the play of presence and absence that is being itself. Heidegger focuses especially on the poetry of Friedrich Hölderlin.

Against the revealing power of poetry, Heidegger sets the force of technology. The essence of technology is the conversion of the whole universe of beings into an undifferentiated "standing reserve" (Bestand) of energy available for any use to which humans choose to put it. Heidegger described the essence of technology as Gestell, or "enframing." Heidegger does not unequivocally condemn technology; he believes that its increasing dominance might make it possible for humanity to return to its authentic task of the stewardship of being. Nevertheless, numerous commentators have concluded that an agrarian nostalgia permeates his later work.

Heidegger's important later works include Vom Wesen der Wahrheit ("On the Essence of Truth," 1930), Der Ursprung des Kunstwerkes ("The Origin of the Work of Art," 1935), Bauen Wohnen Denken ("Building Dwelling Thinking," 1951), and Die Frage nach der Technik ("The Question Concerning Technology," 1954) and Was heisst Denken? ("What Is Called Thinking?" 1954). Also important is Beiträge zur Philosophie (Vom Ereignis) (Contributions to Philosophy [From Enowning]), composed in the years 1936–38 but not published until 1989, on the centennial of Heidegger's birth.

Aristotle and the Greeks

Heidegger was influenced at an early age by Aristotle, mediated through Christian theology, Medieval philosophy, and Franz Brentano. Aristotle's ethical, logical, and metaphysical works were crucial to the development of his thought in the 1920s. Although he later worked less on Aristotle, Heidegger recommended postponing reading Nietzsche, and to "first study Aristotle for ten to fifteen years."

The idea of asking about being may be traced back via Aristotle to Parmenides. Heidegger claimed to have revived the question of being, the question having been largely forgotten by the metaphysical tradition extending from Plato to Descartes, a forgetfulness extending to the Age of Enlightenment and then to modern science and technology. In pursuit of the retrieval of this question, Heidegger spent considerable time reflecting on ancient Greek thought, in particular on Plato, Parmenides, Heraclitus, and Anaximander, as well as on the tragic playwright Sophocles.

Dilthey

Heidegger's very early project of developing a "hermeneutics of factical life" and his hermeneutical transformation of phenomenology was influenced in part by his reading of the works of Wilhelm Dilthey. Heidegger's portrayal of history, historicity, and generation need to be interpreted in this context and, in particular, the correspondence between Dilthey and Paul Yorck von Wartenburg.

Of the influence of Dilthey, Hans-Georg Gadamer writes the following: "As far as Dilthey is concerned, we all know today what I have known for a long time: namely that it is a mistake to conclude on the basis of the citation in Being and Time that Dilthey was especially influential in the development of Heidegger's thinking in the mid-1920s. This dating of the influence is much too late." He adds that by the fall of 1923 it was plain that Heidegger felt "the clear superiority of Count Yorck over the famous scholar, Dilthey." Gadamer nevertheless makes clear that Dilthey's influence was important in helping the youthful Heidegger "in distancing himself from the systematic ideal of Neo-Kantianism, as Heidegger acknowledges in Being and Time." Based on Heidegger's earliest lecture courses, in which Heidegger already engages Dilthey's thought prior to the period Gadamer mentions as "too late," recent scholars as diverse as Theodore Kisiel and David Farrell Krell have argued for the importance of Diltheyan concepts and strategies in the formation of Heidegger's thought.

Gadamer's views on Heidegger are criticized in many quarters, but there can be no doubt that Heidegger seized upon Dilthey's concept of hermeneutics in much the same way that Husserl had seized on Brentano's idea that all of reality could be explained in terms of a descriptive psychology. Heidegger's novel ideas about ontology required a gestalt formation, not merely a series of logical arguments, in order to demonstrate his fundamentally new paradigm of thinking, and the hermeneutic circle offered a new and powerful tool for the articulation and realization of these ideas.

Husserl

There is disagreement over the degree of influence that Husserl had on Heidegger's philosophical development, just as there is disagreement about the degree to which Heidegger's philosophy is grounded in phenomenology. These disagreements centre around how much of Husserlian phenomenology is contested by Heidegger, and how much this phenomenology in fact informs Heidegger's own understanding.

On the relation between the two figures, Gadamer wrote the following: "When asked about phenomenology, Husserl was quite right to answer as he used to in the period directly after World War I: 'Phenomenology, that is me and Heidegger'." Nevertheless, Gadamer noted that Heidegger was no patient collaborator with Husserl, and that Heidegger's "rash ascent to the top, the incomparable fascination he aroused, and his stormy temperament surely must have made Husserl, the patient one, as suspicious of Heidegger as he always had been of Max Scheler's volcanic fire."

Robert J. Dostal understands the importance of Husserl to be profound:

Heidegger himself, who is supposed to have broken with Husserl, bases his hermeneutics on an account of time that not only parallels Husserl's account in many ways but seems to have been arrived at through the same phenomenological method as was used by Husserl. [...] The differences between Husserl and Heidegger are significant, but if we do not see how much it is the case that Husserlian phenomenology provides the framework for Heidegger's approach, we will not be able to appreciate the exact nature of Heidegger's project in Being and Time or why he let it unfinished.

Daniel O. Dahlstrom sees Heidegger's presentation of his work as a departure from Husserl as unfairly misrepresenting Husserl's own work. Dahlstrom concludes his consideration of the relation between Heidegger and Husserl as follows:

Heidegger's silence about the stark similarities between his account of temporality and Husserl's investigation of internal time-consciousness contributes to a misrepresentation of Husserl's account of intentionality. Contrary to the criticisms Heidegger advances in his lectures, intentionality (and, by implication, the meaning of 'to be') in the final analysis is not construed by Husserl as sheer presence (be it the presence of a fact or object, act or event). Yet for all its "dangerous closeness" to what Heidegger understands by temporality, Husserl's account of internal time-consciousness does differ fundamentally. In Husserl's account the structure of protentions is accorded neither the finitude nor the primacy that Heidegger claims are central to the original future of ecstatic-horizonal temporality.

Kierkegaard

Heidegger was also influenced by Søren Kierkegaard. Heidegger's concepts of anxiety (Angst) and mortality draw on Kierkegaard and are indebted to the way in which the latter lays out the importance of our subjective relation to truth, our existence in the face of death, the temporality of existence, and the importance of passionate affirmation of one's individual being-in-the-world. Nonetheless, it is important to notice the difference between the Danish philosopher, whose thought was both individualistic and Christian, and Heidegger, who conceived of human existence as thoroughly social and sharply distinguished philosophy itself from all personal, scientific, and religious commitments.

Contemporary Heideggerians regard Kierkegaard as by far the greatest philosophical contributor to Heidegger's own existentialist concepts. And although Heidegger was careful to point out the highly technical differences between his own philosophy and the traditional definition of existentialism, he is nonetheless regarded by existentialists as one of the most important existential philosophers, on a par with Kierkegaard, Nietzsche, Jaspers and Sartre.

Hölderlin and Nietzsche

Friedrich Hölderlin and Friedrich Nietzsche were both important influences on Heidegger, and many of his lecture courses were devoted to one or other of these figures, especially in the 1930s and 1940s. The lectures on Nietzsche focused on fragments posthumously published under the title The Will to Power, rather than on Nietzsche's published works. Heidegger read The Will to Power as the culminating expression of Western metaphysics, and the lectures are a kind of dialogue between the two thinkers.

This is also the case for the lecture courses devoted to the poetry of Friedrich Hölderlin, which became an increasingly central focus of Heidegger's work and thought. Heidegger grants to Hölderlin a singular place within the history of being and the history of Germany, as a herald whose thought is yet to be "heard" in Germany or the West. Many of Heidegger's works from the 1930s onwards include meditations on lines from Hölderlin's poetry, and several of the lecture courses are devoted to the reading of a single poem (see, for example, Hölderlin's Hymn "The Ister").

Some writers on Heidegger see possibilities within it for dialogue with traditions of thought outside of Western philosophy, particularly East Asian thinking. Despite perceived differences between Eastern and Western philosophy, some of Heidegger's later work, particularly "A Dialogue on Language between a Japanese and an Inquirer," does show an interest in initiating such a dialogue. Heidegger himself had contact with a number of leading Japanese intellectuals, including members of the Kyoto School, notably Hajime Tanabe, Kuki Shūzō and Kyoshi Miki.

Furthermore, it has also been claimed that a number of elements within Heidegger's thought bear a close parallel to Eastern philosophical ideas, particularly with Zen Buddhism and Taoism. An account given by Paul Hsao (in Heidegger and Asian Thought) records a remark by Chang Chung-Yuan claiming that "Heidegger is the only Western Philosopher who not only intellectually understands but has intuitively grasped Taoist thought."

Adolf Hitler was named Chancellor of Germany on January 30, 1933. Heidegger was elected Rector of the University of Freiburg on April 21, 1933, assuming the position the following day, and on May 1 he joined the Nazi Party. Heidegger delivered his inaugural address, the Rektoratsrede, on May 27. It was entitled "The Self-Assertion of the German University," and became notorious. His tenure as Rector was, however, fraught from the beginning. He offered his resignation on April 23, 1934, and it was accepted on April 27. Heidegger remained a member of the academic faculty, and he also remained a member of the Nazi party until the end of the war.

Philosophical historian Hans Sluga places Heidegger's embrace of National Socialism during this period within the context of a similar and often even more enthusiastic acceptance of Nazism from many other German philosophers. He characterises Heidegger's stance while rector in the following way:

Though as rector he prevented students from displaying an anti-Semitic poster at the entrance to the university and from holding a book burning, he kept in close contact with the Nazi student leaders and clearly signaled to them his sympathy with their activism.

In 1945 Heidegger wrote a defence of his term as rector, which he gave to his son Hermann, and which was published in 1983. In it Heidegger referred to his 1933–34 involvement in the following terms:

The rectorate was an attempt to see something in the movement that had come to power, beyond all its failings and crudeness, that was much more far-reaching and that could perhaps one day bring a concentration on the Germans' Western historical essence. It will in no way be denied that at the time I believed in such possibilities and for that reason renounced the actual vocation of thinking in favor of being effective in an official capacity. In no way will what was caused by my own inadequacy in office be played down. But these points of view do not capture what is essential and what moved me to accept the rectorate.

On April 14, 1933 (thus prior to Heidegger's rectorship), Husserl was given an enforced leave of absence because he was Jewish. It is not true, as is sometimes claimed, that during the rectorate Heidegger denied Husserl access to the university library. He did, however, break off contact with Husserl, other than via a "go-between" (though Heidegger claimed that the relationship with Husserl had already become strained after Husserl publicly "settled accounts" with Heidegger and Max Scheler in the early 1930s). Heidegger did not attend his mentor's cremation in 1938, and in 1941, under pressure from publisher Max Niemeyer, agreed to remove the dedication to Husserl from Being and Time (restored in post-war editions).

After the spectacular failure of Heidegger's rectorship, he withdrew from political activity, without canceling his membership of the NSDAP. Nevertheless, references to National Socialism continued to appear in his work, usually in ambiguous ways.

In the course of his 1935 lectures, Heidegger referred to the "inner truth and greatness of this movement" (die innere Wahrheit und Größe dieser Bewegung), that is, of National Socialism. This phrase remained when the lectures were published in 1953 under the title, An Introduction to Metaphysics; however, Heidegger added a parenthetical qualification, without mentioning this change at the time of publication: "(namely, the confrontation of planetary technology and modern humanity) (nämlich die Begegnung der planetarisch bestimmten Technik und des neuzeitlichen Menschen)."

In the lectures of 1942, published posthumously as Hölderlin's Hymn "The Ister", Heidegger makes the following remark:

Today—if one still reads such books at all—one can scarcely read a treatise or book on the Greeks without everywhere being assured that here, with the Greeks, "everything" is "politically" determined. In the majority of "research results," the Greeks appear as the pure National Socialists. This overenthusiasm on the part of academics seems not even to notice that with such "results" it does National Socialism and its historical uniqueness no service at all, not that it needs this anyhow.

Karl Löwith met Heidegger in 1936 while the latter was visiting Rome to lecture on Hölderlin. In an account set down in 1940 and not intended for publication, Löwith recounted an exchange with Heidegger over editorials published in the Neue Zürcher Zeitung:

[I] told him that I did not agree either with the way in which Karl Barth was attacking him or in the way [Emil] Staiger was defending him, because my opinion was that his taking the side of National Socialism was in agreement with the essence of his philosophy. Heidegger told me unreservedly that I was right and developed his idea by saying that his idea of historicity [Geschichtlichkeit] was the foundation for his political involvement.

Löwith went on to say:

In response to my remark that I could understand many things about his attitude, with one exception, which was that he would permit himself to be seated at the same table with a figure such as Julius Streicher (at the German Academy of Law), he was silent at first. At last he uttered this well-known rationalisation (which Karl Barth saw so clearly), which amounted to saying that "it all would have been much worse if some men of knowledge had not been involved." And with a bitter resentment towards people of culture, he concluded his statement: "If these gentlemen had not considered themselves too refined to become involved, things would have been different, but I had to stay in there alone." To my reply that one did not have to be very refined to refuse to work with a Streicher, he answered that it was useless to discuss Streicher; the Stürmer was nothing more than "pornography." Why didn't Hitler get rid of this sinister individual? He didn't understand it.

For commentators such as Habermas who credit Löwith's account, there are a number of generally shared implications: one is that Heidegger did not turn away from National Socialism per se but became deeply disaffected with the official philosophy and ideology of the party, as embodied by Alfred Bäumler or Alfred Rosenberg, whose biologistic racist doctrines he never accepted.

Heidegger's affair with Hannah Arendt, who was Jewish, occurred some time before Heidegger's involvement in National Socialism, but her friendship with Heidegger did not end when she moved to Heidelberg to continue her studies under Karl Jaspers. Arendt later spoke on his behalf at his denazification hearings. Jaspers spoke against him at the same hearings, suggesting he would have a detrimental influence on German students because of his powerful teaching presence. Arendt cautiously resumed their friendship after the war, despite or even because of the widespread contempt for Heidegger and his political sympathies. The denazification hearings resulted in Heidegger being forbidden to teach between 1945 and 1951. One consequence of his disfavour in Germany was that Heidegger began to engage far more in the French philosophical scene.

In a lecture on technology delivered at Bremen in 1949, Heidegger made the following controversial remark:

Agriculture is now a motorized food industry, the same thing in its essence as the production of corpses in the gas chambers and the extermination camps, the same thing as blockades and the reduction of countries to famine, the same thing as the manufacture of hydrogen bombs.

This quotation has been the subject of widespread criticism and interpretation. Philippe Lacoue-Labarthe, for example, described it as "scandalously inadequate."

In 1967 Heidegger had an encounter with the Jewish poet, Paul Celan, who had been interned during the war. On July 24 Celan gave a reading at the University of Freiburg, attended by Heidegger. Heidegger there presented Celan with a copy of What is Called Thinking?, and invited him to visit him at his hut at Todtnauberg, an invitation which Celan accepted. On July 25 Celan visited Heidegger at his retreat, signing the guestbook and spending some time walking and talking with Heidegger. The details of their conversation are not known, but the meeting was the subject of a subsequent poem by Celan, entitled "Todtnauberg" (dated August 1, 1967). The enigmatic poem and the encounter have been discussed by numerous writers on Heidegger and Celan, notably Lacoue-Labarthe.

On September 23, 1966, Heidegger gave an interview to Der Spiegel magazine, in which he agreed to discuss his political past provided that the interview be published posthumously (it was published on May 31, 1976). In the interview, Heidegger defended his entanglement with National Socialism in two ways: first, he argued that there was no alternative, saying that he was trying to save the university (and science in general) from being politicized and thus had to compromise with the Nazi administration. Second, he admitted that he saw an "awakening" ("Aufbruch") which might help to find a "new national and social approach" but stated that he changed his mind about this in 1934, largely prompted by the violence of the Night of the Long Knives.

The Löwith account from 1936 has been cited to contradict the account given in the Spiegel interview in two ways: that there was no decisive break with National Socialism in 1934 and that Heidegger was willing to entertain more profound relations between his philosophy and political involvement. The Der Spiegel interviewers did not bring up Heidegger's 1949 quotation comparing the industrialization of agriculture to the extermination camps. In fact, the Der Spiegel interviewers were not in possession of much of the evidence now known for Heidegger's Nazi sympathies.

Heidegger was one of the most influential philosophers of the 20th century, and his ideas have penetrated into many areas, but in France there is a very long and particular history of reading and interpreting his work.

Heidegger's influence on French philosophy began in the 1930s, when Being and Time, "What is Metaphysics?" and other Heideggerian texts were read by Jean-Paul Sartre and other existentialists, as well as by thinkers such as Emmanuel Lévinas, Alexandre Kojève and Georges Bataille. Because Heidegger's discussion of ontology (the study of being) is rooted in an analysis of the mode of existence of individual human beings (Dasein, or being-there), his work has often been associated with existentialism. The influence of Heidegger on Sartre's Being and Nothingness is marked, but Heidegger felt this influence took the form of a misreading, as he argued in later texts such as the "Letter on 'Humanism'." In that text, intended for a French audience, Heidegger explained this misreading in the following terms:

Sartre's key proposition about the priority of existentia over essentia [that is, Sartre's statement that "existence precedes essence"] does, however, justify using the name "existentialism" as an appropriate title for a philosophy of this sort. But the basic tenet of "existentialism" has nothing at all in common with the statement from Being and Time [that "the 'essence' of Dasein lies in its existence"]—apart from the fact that in Being and Time no statement about the relation of essentia and existentia can yet be expressed, since there it is still a question of preparing something precursory.

After the war, Heidegger was banned from university teaching for a period on account of his activities as Rector of Freiburg University. He developed a number of contacts in France, where his work continued to be taught, and a number of French students visited him at Todtnauberg (see, for example, Jean-François Lyotard's brief account in Heidegger and "the jews", which discusses a Franco-German conference held in Freiburg in 1947, one step toward bringing together French and German students). Heidegger subsequently made several visits to France, and made efforts to keep abreast of developments in French philosophy by way of correspondence with Jean Beaufret, an early French translator of Heidegger, and with Lucien Braun.

Deconstruction came to Heidegger's attention in 1967 by way of Lucien Braun's recommendation of Jacques Derrida's work (Hans-Georg Gadamer was present at an initial discussion and indicated to Heidegger that Derrida's work came to his attention by way of an assistant). Heidegger expressed interest in meeting Derrida personally after the latter sent him some of his work. There was discussion of a meeting in 1972, but this failed to take place. Heidegger's interest in Derrida is said by Braun to have been considerable (as is evident in two letters, of September 29, 1967 and May 16, 1972, from Heidegger to Braun). Braun also brought to Heidegger's attention the work of Michel Foucault. Foucault's relation to Heidegger is a matter of considerable difficulty; Foucault acknowledged Heidegger as a philosopher whom he read but never wrote about. (For more on this see Penser à Strasbourg, Jacques Derrida, et al, which includes reproductions of both letters and an account by Braun, "À mi-chemin entre Heidegger et Derrida").

Jacques Derrida made emphatic efforts to displace the understanding of Heidegger's work that had been prevalent in France from the period of the ban against Heidegger teaching in German universities, which amounted to an almost wholesale rejection of the influence of Jean-Paul Sartre and existentialist terms. In Derrida's view, deconstruction is a tradition inherited via Heidegger (the French term "déconstruction" is a term coined to translate Heidegger's use of the words "Destruktion" - literally "destruction" - and "Abbau" - more literally "de-building"). According to Derrida, Sartre's interpretation of Dasein and other key Heideggerian concerns is overly psychologistic, anthropocentric, and misses the historicality central to Dasein in Being and Time. Sartre's reading of Heidegger, which formed the basis of the former's major work Being and Nothingness, was based on limited number of Heidegger's texts commonly studied in France up to that point (namely Being and Time, What is Metaphysics? and Kant and the Problem of Metaphysics). Because of his vehement attempts to "rescue" Heidegger from his existentialist interpreters, Derrida has at times been represented as an ultra-orthodox "French Heidegger," to the extent that he, his colleagues, and his former students are made to go proxy for Heidegger's worst (political) mistakes, despite ample evidence that the reception of Heidegger's work by later practitioners of deconstruction is anything but doctrinaire. The work of Philippe Lacoue-Labarthe may be taken as exemplary in this regard and was often commended as such by Derrida, who further contrasted Lacoue-Labarthe's extended work on Heidegger with Foucault's silence.

In consideration of the contributions of Derrida, Lacoue-Labarthe, and Lyotard to scholarship on Heidegger and his ties to National Socialism, it is worth noting that Heidegger's relation to the Holocaust and Nazism was the subject of great and occasionally fractious debate across various "deconstructions". These included the extent to which specific practitioners of deconstruction could entirely do without Heideggerian deconstruction (as Lyotard in particular may have wished) or were - rather - obliged to further (and in the cases of many mis- and uninformed criticisms, recall) already extensive criticisms of Heidegger which considerably predated (in the case of Derrida, by decades) the broad recognition of Heidegger's activities as a National Socialist. The latter were precipitated by press attention to the Víctor Farías book "Heidegger et le nazisme" (Farías was an ex-student of Heidegger) and extensive treatments of the Holocaust and its implications. These included for example, the proceedings of the first conference dedicated to Derrida's work, published as "Les fins de l'homme" (the essay from which that title was taken), Derrida's "Feu la cendre/cio' che resta del fuoco", or the studies on Paul Celan by Lacoue-Labarthe and Derrida which shortly preceded the detailed studies of Heidegger's politics published in and after 1987.

More recently, Heidegger's thought has considerably influenced the work of the French philosopher Bernard Stiegler. This is evident even from the title of Stiegler's multi-volume magnum opus, La technique et le temps (volume one translated into English as Technics and Time, 1: The Fault of Epimetheus). Stiegler offers an original reading of Heidegger, arguing that there can be no access to "originary temporality" other than via material, that is, technical, supports, and that Heidegger recognised this in the form of his account of world historicality, yet in the end suppressed that fact. Stiegler understands the existential analytic of Being and Time as an account of psychic individuation, and his later "history of being" as an account of collective individuation. He understands many of the problems of Heidegger's philosophy and politics as the consequence of Heidegger's inability to integrate the two.

Heidegger's influence upon 20th century continental philosophy is unquestioned and has produced a variety of critical responses.

The content of Being and Time, according to Husserl, claimed to deal with ontology, but from Husserl's perspective only did so in the first few pages of the book. Having nothing further to contribute to an ontology independent of human existence, Heidegger changed the topic to Dasein. Whereas Heidegger argued that the question of human existence is central to the pursuit of question of being, Husserl criticized this as reducing phenomenology to "philosophical anthropology" and offering an abstract and incorrect portrait of the human being.

The Neo-Kantian Ernst Cassirer and Heidegger engaged in an influential debate located in Davos in 1929, concerning the significance of Kantian notions of freedom and rationality. Whereas Cassirer defended the role of rationality in Kant, Heidegger argued for the priority of the imagination. Dilthey's student Georg Misch wrote the first extended critical appropriation of Heidegger in Lebensphilosophie und Phänomenologie. Eine Auseinandersetzung der Diltheyschen Richtung mit Heidegger und Husserl, Leipzig 1930 (3. ed. Stuttgart 1964).

Marxist influenced thinkers, especially György Lukács and the Frankfurt School, associated the style and content of Heidegger's thought with German irrationalism and criticized its political implications.

Initially members of the Frankfurt School were positively disposed to Heidegger, becoming more critical at the beginning of the 1930s. Heidegger's student Herbert Marcuse became associated with the Frankfurt School. Initially striving for a synthesis between Hegelian-Marxism and Heidegger's phenomenology, Marcuse later rejected Heidegger's thought for its "false concreteness" and "revolutionary conservativism." Theodor Adorno wrote an extended critique of the ideological character of Heidegger's early and later use of language in the Jargon of Authenticity. Contemporary social theorists associated with the Frankfurt School have remained critical of Heidegger's works and influence. In particular, Jürgen Habermas admonishes the influence of Heidegger on recent French philosophy in his polemic against "postmodernism" in The Philosophical Discourse of Modernity (1985).

Heidegger's politics and style has been criticized by Richard Wolin and Tom Rockmore, the latter arguing that Being and Time does not follow the norms of scholarly writing, i.e. defining new terms as they are introduced. Rockmore and other critics say this was due to an authoritarian style.

Criticism of Heidegger's philosophy has also come from analytic philosophy, beginning with logical positivism. Accusing Heidegger of offering an "illusory" ontology, Rudolf Carnap criticized him, in "The Elimination of Metaphysics Through Logical Analysis of Language" (1932), of committing the fallacy of reification and of wrongly dismissing the logical treatment of language, which, according to Carnap, can only lead to writing "nonsensical pseudo-propositions."

A ferocious critic of Heidegger's philosophy was the British logical positivist A. J. Ayer, who categorizes philosophers into laymen, pontiffs, and journeymen in The Meaning of Life. The pontiffs (whom Ayer considered to be the worst of the three categories) were philosophers who, according to Ayer, proposed vast, overarching theories regarding existence, which are completely unverifiable through empirical demonstration and logical analysis. For Ayer, this sort of philosophy was a poisonous strain in modern thought and he considered Heidegger to be the "arch-pontiff" of the classification, because of Heidegger's repudiation of the importance of reason and his invention of theories that seem empirically unverifiable. Ayer believed that pontification was entirely useless.

Bertrand Russell commented, expressing the sentiments of many mid-20th-century English-speaking philosophers, that: "his philosophy is extremely obscure. One cannot help suspecting that language is here running riot. An interesting point in his speculations is the insistence that nothingness is something positive. As with much else in Existentialism, this is a psychological observation made to pass for logic."

The analytic tradition values clarity of expression. For Heidegger, however, intelligibility is 'suicide for philosophy'. He stated, in opposition to positivism, that "those in the crossing must in the end know what is mistaken by all urging for intelligibility: that every thinking of being, all philosophy, can never be confirmed by 'facts,' i.e., by beings. Making itself intelligible is suicide for philosophy. Those who idolize 'facts' never notice that their idols only shine in a borrowed light. They are also meant not to notice this; for thereupon they would have to be at a loss and therefore useless. But idolizers and idols are used wherever gods are in flight and so announce their nearness." Apart from the charge of obscurantism, other analytic philosophers considered the actual content of Heidegger's work to be either faulty and frivolous, subjective or uninteresting.

However, not all analytic philosophers have been as hostile. Gilbert Ryle wrote a critical yet positive review of Being and Time and Ludwig Wittgenstein made some positive remarks in passing that only recently have seen the light of day. These positive and negative analytic evaluations have been collected in Michael Murray (ed.), Heidegger and Modern Philosophy: Critical Essays (Yale University Press, 1978). Heidegger's reputation within English-language philosophy has improved in philosophical terms in some part through the efforts of Hubert Dreyfus, Richard Rorty, and a recent generation of analytically-oriented phenomenology scholars. Pragmatist Rorty claimed that Heidegger's approach to philosophy in the first half of his career has much in common with that of the latter-day Ludwig Wittgenstein, a significant figure in analytical philosophy.

Although Heidegger is often thought to be the most influential philosopher of the 20th century in continental philosophy, the significance of his work has been debated even by philosophers sympathetic to some aspects of his work, such as Hans-Georg Gadamer and Jacques Derrida. However, rather than universal denouncements of his style, these criticisms tend to engage Heidegger's thought more substantively on the basis of content, including issues such as the priority of ontology, the status of animals, the nature of the religious, Heidegger's apparent neglect of ethics (Emmanuel Lévinas), the body (Maurice Merleau-Ponty), or air (Luce Irigaray).

Emmanuel Lévinas was deeply influenced by Heidegger yet became one of his fiercest critics, contrasting the infinity of the good beyond being with the immanence and totality of ontology. Continental philosophy of religion is critical of Heidegger's perceived "atheism" (because of the early Heidegger's description of philosophy as "methodologically atheist") and/or "paganism" (because of his use of expressions such as earth and sky, mortals and immortals).

The new materialism from Gilles Deleuze to Antonio Negri and Alain Badiou has contested what they perceive to be the idealistic residue at work in Heidegger's account of human existence as understanding (verstehen).

* The Ister (2004) is a film based on Heidegger's 1942 lecture course on Friedrich Hölderlin, and features Jean-Luc Nancy, Philippe Lacoue-Labarthe, Bernard Stiegler, and Hans-Jürgen Syberberg. The official site is located here. * The film director Terrence Malick translated Heidegger's 1929 essay "Vom Wesen des Grundes" into English. It was published under the title The Essence of Reasons (Evanston: Northwestern University Press, 1969, bilingual edition).

Heidegger's collected works are published by Vittorio Klostermann. The Gesamtausgabe was begun during Heidegger's lifetime. He defined the order of publication and controversially dictated that the principle of editing should be "ways not works." Publication has not yet been completed.

The contents are listed here: Gesamtausgabe.

A complete list of English translations of Heidegger's work is available here.

* Hubert Dreyfus, Being-in-the-World: A Commentary on Heidegger's Being and Time, Division I * Theodore Kisiel, The Genesis of Heidegger's Being and Time * Stephen Mulhall, Heidegger and Being and Time

* Victor Farias, Heidegger and Nazism (a disputed and controversial biography; see, for instance, Pierre Joris here) * Hugo Ott, Martin Heidegger: A Political Life * Rüdiger Safranski, Martin Heidegger: Between Good and Evil

* Pierre Bourdieu, The Political Ontology of Martin Heidegger * Miguel de Beistegui, Heidegger and the Political: Dystopias * Jacques Derrida, Of Spirit: Heidegger and the Question * Dominique Janicaud, The Shadow of That Thought * Philippe Lacoue-Labarthe, "Transcendence Ends in Politics," in Typography: Mimesis, Philosophy, Politics * Philippe Lacoue-Labarthe, Heidegger, Art, and Politics: The Fiction of the Political * Karl Löwith, Martin Heidegger and European Nihilism * Jean-François Lyotard, Heidegger and "the jews" * Günther Neske & Emil Kettering (eds.), Martin Heidegger and National Socialism: Questions and Answers * Hans Sluga, Heidegger's Crisis: Philosophy and Politics in Nazi Germany * Richard Wolin (ed.), The Heidegger Controversy ISBN 0-262-23166-2.

* Robert Bernasconi, Heidegger in Question: The Art of Existing * Walter A. Brogan, Heidegger and Aristotle: The Twofoldness of Being * Jacques Derrida, "Ousia and Gramme: Note on a Note from Being and Time," in Margins of Philosophy * Paul Edwards, Heidegger's Confusions * Christopher Fynsk, Heidegger: Thought and Historicity * Hans Köchler, God in the Thought of Martin Heidegger, in: S. A. Matczak (ed.), God in Contemporary Thought * Philippe Lacoue-Labarthe, Poetry as Experience * Philippe Lacoue-Labarthe, Heidegger and the Politics of Poetry * William McNeill, The Glance of the Eye: Heidegger, Aristotle, and the Ends of Theory * William McNeill, The Time of Life: Heidegger and Ethos * Jean-Luc Nancy, "The Decision of Existence," in The Birth to Presence * Herman Philipse, Heidegger's Philosophy of Being: A Critical Interpretation * Richard Polt, Heidegger: An Introduction * François Raffoul, Heidegger and the Subject * François Raffoul and David Pettigrew (ed), Heidegger and Practical Philosophy * John Sallis, Echoes: After Heidegger * John Sallis (ed), Reading Heidegger: Commemorations, including articles by Robert Bernasconi, Jacques Derrida, Rodolphe Gasché, and John Sallis, among others. * Reiner Schürmann, Heidegger on Being and Acting: From Principles to Anarchy * Bernard Stiegler, Technics and Time, 1: The Fault of Epimetheus * Iain Thomson, Heidegger on Ontotheology Technology and the Politics of Education * Andrzej Warminski, Readings in Interpretation: Hölderlin, Hegel, Heidegger

* Jean Beaufret, Dialogue avec Heidegger, 4 vols. * Dominique Janicaud, Heidegger en France, 2 vols. * Ethan Kleinberg, Generation Existential: Heidegger's Philosophy in France, 1927-1961

* Aletheia * Heideggerian terminology * Hölderlin's Hymn "The Ister" * Ontotheology * Philosophy of education (Martin Heidegger)

* German Heidegger Society. * Heidegger information in English: Ereignis. * Heidegger.org.uk. * Phainomena – Heidegger-blog: literature, activities and news about Heidegger and his philosophy.

* English translations of Heidegger's works. * Complete contents of the Gesamtausgabe.

* "Martin Heidegger" <nowiki>[Internet Encyclopedia of Philosophy</nowiki>] – informative article, summarizing Heidegger's philosophy, including his theories on Angst, and criticisms from other philosophers such as Husserl. * Books introducing Heidegger. * – a positive review of Walter Kaufmann's and George Steiner's negative treatments of Heidegger. * Hearing Heidegger and Saussure by Elmer G. Wiens. * "Viewing Power in Heidegger and Levinas" by Mitchell Cowen Verter. * "Serious response to Emmanuel Faye on Heidegger and nazism". * "Nazi foundations of Heidegger's Work" by Emmanuel Faye, with a discussion. * "For the opening of Heidegger's Archives" by Emmanuel Faye. * Réponses de Gérard Guest (1) (au dossier publié dans "Magazine Littéraire"). * Réponses de Gérard Guest (2) (au dossier publié dans "Le Point"). * Heidegger: Universitätsbibliothek Freiburg im Breisgau (Multilingual). * Being and Power: Heidegger and Foucault by Hubert Dreyfus. * http://ist-socrates.berkeley.edu/~hdreyfus/html/papers.html Recent Papers by Hubert Dreyfus. * Martin Heidegger on Alethéia and the History of Metaphysics as Ontotheology. * François Fédier: Avant-Propos: Heidegger à plus forte raison, Fayard, Paris, 2007. * François Fédier: Mécanique de la diffamation. * Heidegger contre le nazisme (blog Sorbonne-Paris4). *A Normal Nazi Thomas Sheehan on Heidegger *Heidegger and Nazism: An Exchange

* Human all too human : Martin Heidegger - BBC documentary. * Heidegger Speaks. Part 1. English subtitled. (YouTube). * Martin Heidegger. Teil 2. German. 1975 (YouTube). * François Fédier, Pascal David et Faye.Multimedia. * Heidegger speaking. * Podcast of Prof. Hubert Dreyfus' undergraduate lectures on Heidegger.