If Martin Heidegger is the most important thinker of the twentieth century, this is partly because of his remarkable effect on several major political thinkers who made responding to his life and thought critical to their work. Theodor Adorno, Herbert Marcuse, Hannah Arendt, Hans Jonas, and even Jürgen Habermas found replying to Heidegger necessary for the development of their own philosophic projects.

In a recent volume of the excellent series New Heidegger Research we have the correspondence between Heidegger and the first of his independently and intellectually significant students. Karl Löwith is the author of From Hegel to Nietzsche, Nietzsche's Philosophy of the Eternal Recurrence of the Same, Meaning in History, and other important works of political philosophy, including penetrating interpretations of Heidegger. He was close friends with others of Heidegger's students, Hans-Georg Gadamer and Gerhard Kruger, and with their mutual friend Leo Strauss. After studying with Heidegger and Husserl at Freiburg in the early 1920s, Löwith went on to habilitate under Heidegger (one of only five students to do so) while he taught at Marburg. Löwith fled the Nazis, first to Italy, then to Japan, then to the United States; he returned to Germany in the late 1940s. Löwith documents the early part of this peregrination in a remarkable set of memoirs entitled My Life in Germany before and after 1933.

The new volume of letters, translated by J. Goesser Assaiante and S. Montgomery Ewegen, opens a tremendous new pathway through some of the richest contestations in twentieth-century thought. Originally published in German in 2015, it consists in 122 letters between Löwith and Heidegger, dating from 1919 until Löwith's death in 1973. The vast bulk of the letters are exchanged between 1919 and 1928, all but terminating in 1934 with Löwith's flight from Germany and Heidegger's assumption of duties for the Nazi regime at the University of Freiburg. In the later ’40s a smattering of more or less practical letters (scheduling personal meetings and so forth) reappear.

The earliest phase of the correspondence shows a brilliant, powerful teacher well-pleased with a capable and eager student, a seemingly near-peer who understands him and appreciates his philosophic mission in ways that his colleagues and academic superiors manifestly do not. In these early letters both of them are eager to converse and extend the explorations of their ongoing conversations. But after Heidegger leaves his position at Freiburg for a more prestigious and secure position at Marburg, the distance between them seems to grow; Heidegger reports being less connected to his students than he had been among the group at Freiburg of whom Löwith had been a member. Heidegger's retreat from discussing the substance of his work with Löwith is conspicuous by its absence. For example, he reports virtually nothing of his epochal Davos exchange with Cassirer to Löwith, mentioning only that he “did have the opportunity to go on a few wonderful ski trips” (132, letter 94). Though there are several references to the need for conversation to explore serious topics, this had not prevented such matters from being discussed earlier in their correspondence. Through this period Löwith's letters to Heidegger remain long and effusive.

The exchanges have much to them of what might be called academic gossip: shared frustrations with Edmund Husserl, Karl Jaspers, and others; dissatisfactions with the pretensions of the German academy; assessments of Heidegger's other students. Such discussions often border on the very mundane (there are innumerable discussions of money) but occasionally rise to the level of the genuinely illuminating. Heidegger's criticisms of the university are adjacent to his philosophic critique of the modern West, and it was the prospect of reforming the university (a concern of high pedigree in German philosophy since at least Fichte) that drew him into his catastrophic and noxious political activity with the Nazis. His bitterness about university life in these letters is oddly significant, then. When Löwith habilitates, Heidegger warns him: “In the future, do not be too surprised if you come to experience more, and more powerfully, the demoralization of the university” (131, letter 92).

For scholars of political theory, these letters indicate the radicality of Heidegger's project. By pairing him with someone—a close student—whose connection to the traditional concerns of ethical and political philosophy is more visible, the remaining differences appear all the more starkly. This comes through in Löwith's first gestures at a critique of Heidegger and Heidegger's response. In his habilitation, Löwith attempts to develop an ethics founded on a philosophic anthropology where the identity of an individual is mediated through his involvements with another. Löwith understands himself to be drawing from Heidegger's phenomenological demonstration that any theory is always implicitly drawn from the factical world of our shared existence. In his view, he is both developing a potentiality indicated by Heidegger and criticizing Heidegger for not exploring such a possibility himself.

Heidegger rejects this approach. A finished “anthropology” is not at our disposal, he attests, because we have yet adequately to clarify the more fundamental issue of Being, more precisely, the meaning of Being. And while it is true that the analytic of (human) Dasein bears a certain superficial resemblance to an “anthropology,” taking it as such grossly misunderstands its position in Heidegger's argument as an introduction to and clarification of the question of Being. Thus, Heidegger denies the suitability of his analytic of Dasein as a basis for any other discipline or study—including a clarification, as pursued by Löwith, of the ethical “I-Thou problem”— prior to having clarified with precision the problems of ontology. His charge against Löwith is, in sum, that Löwith has too hastily proceeded from unclarified premises to construct a new anthropology (which then serves as premises for critiquing other positions). For his part, Heidegger insists that the only necessary determination to be uncovered via the hermeneutics of facticity is the problematics of ontology. For decades to come, Heidegger will decry the erroneous reading of Being and Time as having supplied an “anthropology.” It would seem that Löwith's, according to Heidegger, is the first such misreading. Heidegger is thus quite, quite far from thinking it proper to compose an “ethics,” let alone a “politics,” in anything like the traditional sense of these philosophic disciplines.

Given the events that proved so important to their lives it is remarkable how absent politics is from the exchanges here. In 1933 Löwith wrote some letters to Heidegger which were not preserved, and Heidegger's only response (included in this volume) is that the matters raised in them are better discussed in person, but unfortunately he is much too busy to write more. Perhaps Löwith raised in those letters something like the concerns he voiced to Heidegger in their later meeting in Rome in 1936, while Löwith was in impoverished exile, namely, how anyone of intellect could join hands with the brutes and swinish thugs of the Nazis. Löwith's line of questioning (recorded in a diary entry from 1936, included as an appendix to this volume) reveals again, perhaps, the limits of his understanding of Heidegger's project. Heidegger claimed that none of his students understood him. Perhaps we have here an ugly indication of this truth.

However one judges the differences between Heidegger and Löwith, and however one assesses Heidegger's political involvements, a consideration of this extraordinarily rich collection will be most profitable. One feels compelled to add in a review of the book that one wishes that the quality of its production were much better in terms of its paper, printing, and binding. This reviewer's copy disintegrated almost immediately upon reading.