Plato’s Sophist by Martin Heidegger, reconstructed from his seminal 1924–25 lecture course at the University of Marburg, is both an extraordinary exposition of Greek philosophy and a key elaboration of Heidegger’s own ontological concerns, bridging the ancient and the modern in a transformative philosophical dialogue. This work is a rigorous philosophical undertaking, threading Plato’s dialogue Sophist through the interpretative lens of Aristotle’s works, especially Nicomachean Ethics Book VI and Metaphysics Book I, while combining it with Heidegger’s contemporaneous development of Being and Time. In this, the work reveals the mutual imbrication of Greek thought with Heidegger’s groundbreaking ontological project.
The primary focus of Heidegger’s interpretation is the thematic and methodological core of Sophist: the ontological distinction between Being and non-being and the epistemic interexchange of truth and semblance. Heidegger’s astonishing, almost line-by-line analysis of Sophist exposes the philosophical rigor underlying Plato’s exploration of the sophist as the antithesis of the philosopher, presenting a vivid contrast that demands the confrontation of Parmenides’ dictum that “non-being is not.” For Heidegger, Plato’s questioning of non-being is not a simple negation but an unveiling of its ontological richness, revealing the complex dynamism between appearance and essence. This dynamism, encapsulated in Plato’s exploration of the sophist’s domain of semblance, becomes a precursor to Heidegger’s own investigations into the nature of truth (as aletheia, or unconcealment) and the ontological status of Dasein, or human existence.
The text begins with Heidegger’s compelling justification for a “double preparation” in interpreting Plato: one must adopt both a phenomenological orientation and a historiographical approach to navigate the obscurities of the Platonic dialogues. Heidegger asserts that Aristotle serves as the clearest guide to Plato, given the Aristotelian elucidation of Being as presence (ousia) and truth as unconcealedness (aletheia), which are central to Plato’s dialectical method in Sophist. Through Aristotle’s explication of aletheia as a mode of Being inseparable from the logos (discourse), Heidegger establishes the philosophical groundwork necessary to approach Plato’s ontology.
In his reconstruction, Heidegger elaborates on Aristotle’s classification of the intellectual virtues in Nicomachean Ethics Book VI as modes of aletheuein—practical wisdom (phronesis), technical knowledge (techne), scientific understanding (episteme), philosophical wisdom (sophia), and intuitive reason (nous). Each of these modes represents a distinct way in which Dasein engages with the world, a theme that Heidegger extends into his interpretation of Plato’s Sophist. The sophist, as a producer of semblances, becomes a paradoxical figure within this framework, operating at the boundary between truth and falsity, reality and illusion, and forcing the philosopher to articulate the Being of non-beings in a way that preserves their ontological significance without succumbing to contradiction.
The methodological heart of Heidegger’s analysis lies in his discussion of the dialectic, the procedural method in Sophist that unveils the structures of Being by navigating the interrelations of fundamental categories such as sameness (tautotes), difference (heterotes), motion (kinesis), and rest (stasis). Heidegger’s reconstruction highlights the koinonia (communality) of the genera, revealing Plato’s groundbreaking insight into the participation of opposites—non-being participates in Being as heteron (the Other), which allows for the very possibility of negation and falsity in discourse.
Heidegger’s central assertion is that Sophist is not merely an exploration of sophistry or a critique of sophistic rhetoric but an ontology of Being of beings and the presence of non-beings. In this way, Plato’s dialogue anticipates Heidegger’s existential analytics of Dasein, wherein the human capacity for uncovering truth (aletheuein) involves not only a confrontation with Being but also an engagement with its concealment and distortion. Heidegger’s interpretation, therefore, transforms Plato’s engagement with the sophist into a philosophical drama of truth-seeking, where the very structures of human understanding and existence are at stake.
The dynamics of Being and language emerges as a pivotal theme, as Heidegger demonstrates how Plato’s emphasis on logos—not as mere speech but as the ontological articulation of the real—lays the foundation for Western metaphysics. In this regard, Sophist becomes, in Heidegger’s hands, a mirror reflecting the unresolved tensions within the Western philosophical tradition, tensions that Heidegger himself seeks to resolve through his own ontology.
For scholars of Heidegger, Plato, or Aristotle, this volume is indispensable not only as an interpretation of Greek philosophy but also as an integral component of Heidegger’s larger philosophical trajectory. Its methodical precision, linguistic acuity, and ontological depth exemplify Heidegger’s capacity to reanimate the Platonic dialogues as living inquiries into the most fundamental questions of philosophy. Readers are invited to participate in this dialogue, confronting the challenges of Being and non-being, truth and semblance, presence and absence, as they resonate across millennia, through Plato and Aristotle, to Heidegger himself.
Analysis
Plato’s Sophist as reconstructed from Heidegger’s Marburg lectures of 1924–25 advances a very precise scholarly stake: it secures, with unusual methodological self-consciousness, an access-path to Plato by first fixing the Greek ground-concepts of aletheuein (disclosing truth) and logos (saying as letting-appear), then re-reading the Sophist as an ontological inquiry into the being of non-beings through the koinōnia of the “greatest kinds.” The distinctive contribution lies in the double preparation that authorizes the reading—phenomenological orientation and hermeneutic reversal from Aristotle back to Plato—and in the resulting claim that the dialogue’s hunt for the sophist is the controlled surface of a deeper trial: the clarification of how falsity, image, and otherness belong intrinsically to the field of being as such.
Heidegger frames the course as an interpretation of Plato’s late work carried out under a “double preparation.” First, there is a philosophical-phenomenological preface: phenomenology means ta phainomena legein, speaking of what shows itself, where the decisive question is the being of what shows itself. This is not a technique but a way into the matters as they give themselves; it learns its craft from the Greeks and from the renewed rigor of questioning since Husserl’s Logical Investigations. The purpose of the preface is modest yet binding: not to school “phenomenologists” but to bring inquiry to the point where the concepts in question—being, non-being, truth, semblance—can be investigated as phenomena rather than presupposed as obvious. This desideratum governs the entire reading. The definitions are not window-dressing; they are methodological gates through which the phenomena may appear. These claims are textually secured in Heidegger’s opening pages.
Secondly, there is a historiographical-hermeneutic preface with a clear principle: interpret “from the clear into the obscure,” namely, from Aristotle to Plato. Aristotle is taken as the guide because he renders explicit the linkage between truth as disclosedness and being—linkage that remains operative yet latent in Plato. On this path the past is not at a distance; we are it insofar as our scientific comportment still stands on Greek foundations that have become “obvious.” Re-appropriation thus requires a guided un-obviousness, a counter-movement that brings into view the unthematic supports of our current understanding. This is not an antiquarian posture; it is a demand generated by the very topics of being and non-being, truth and semblance that the Sophist addresses. These points too are explicitly stated in the preliminary pages and in the translator’s frame that summarizes Heidegger’s rationale for “Aristotle to Plato.”
The initial “securing” of the ground is accomplished through a concentrated interpretation of Aristotle—foremost the Nicomachean Ethics VI and X, and Metaphysics I. The guiding claim is that for Greek Dasein (here: the human way of being) truth is carried out as aletheuein, a mode of life that is tethered to logos: speaking as interpretive letting-appear. Aristotle is thus not a historical detour but the disclosure, in explicit form, of what makes Plato’s questioning possible: truth as a mode of being—indeed, as a mode of the soul—and logos as the mobile medium of revealing and covering. The catalog of aletheuein’s modes—technē, epistēmē, phronēsis, sophia, nous—establishes how Greek life can comport itself toward beings in distinct ways, each with its own truth-function. Heidegger emphasizes that all but nous are “with speech” (meta logou), and even nous is not alien to saying insofar as what is discerned subsequently enters discursive articulation. This analytical platform is presented in the introductory chapters and is continually recalled as the reading of Plato advances.
Within this Aristotelian propaedeutic, two lines become structurally decisive for the later Plato: first, the graded genesis from aisthēsis and empeiria through technē to epistēmē and sophia (Heidegger’s emphasis on “levels” of eidenai), and second, the question of the rank of sophia vis-à-vis phronēsis. The first line—Metaphysics I, 1–2—clarifies how “learning to see” becomes “seeing the universal” and how technē implicitly tends toward a more autonomous epistēmē. The second—Ethics VI and X—shows why “dwelling with the highest things” enjoys priority over practical insight while still leaving a problem: the human being is naturally bound to practical concerns. Heidegger does not flatten this tension; he mobilizes it as a structural prelude to Plato’s own dual framing in the Sophist: the concrete figures (philosopher, sophist) and the pure movement of logos. These expositions are textually anchored where he articulates the five modes of disclosing, the genesis of sophia, and the argument for its priority in relation to eudaimonia.
A first transformation of the ground occurs at the transition where aletheuein becomes dialegesthai: truth as free-standing disclosure is folded into the methodological necessity of dialectic. Heidegger marks this shift as both a continuation and a correction of any naive reliance on “propositional logic.” While logos is the most immediate site where beings show up, it is simultaneously the field of concealment and idle talk; thus dialectic as “breaking through prattle” toward noein (seeing) is required. This is why the course inserts an excursus on Plato’s position on logos by way of rhetoric: the Phaedrus becomes a measured probe into the positive and negative conditions of saying. As the text insists, Plato treats rhetoric as an “psychagōgia,” a leading of the soul, when it is grounded in truth as dialectical seeing; conversely, he criticizes “free-floating logos” and especially writing as a dissemination of seeming knowledge severed from living grasp. Heidegger supplies the legend of Theuth as ontological allegory: writing weakens memory and reduces truth to repeatability, thereby exposing logos’ structural duplicity. These analyses are explicit in the Phaedrus excursus and serve as a bridge into the Sophist’s preoccupation with the seeming that sophistry manufactures.
The outer framing of the Marburg course also deserves to be specified. It opens with an In memoriam to Paul Natorp, whose Plato scholarship exemplified the exacting standard of philosophical understanding to which Heidegger aspires. The course is reconstructed from multiple sources: Heidegger’s manuscript, student notes (Jonas, Schalk, Weiß), and—crucially for the second part—a typewritten copy of S. Moser’s stenographic transcript that Heidegger authorized and annotated. This material history is not an editor’s curiosity; it registers in the texture of the exposition, which alternates dense Greek citation with interpretive paragraphs and occasionally recasts quotations freely for pedagogical reasons. The textual basis and lecture-style alternation are documented in the paratexts and apparatus.
With these groundings, Heidegger turns to the Sophist itself. He accepts a traditional tripartite sense of the dialogue’s structure—introduction, shell, kernel—only to complicate it by showing how the methodological “shell” (the hunt for the sophist through diairetic definitions) continuously presses against the “kernel” (the being of non-beings), so that method and ontology interpenetrate. The opening gesture—the Eleatic Stranger’s role and the recollection of Parmenides—prepares the decisive clash: if the sophist thrives on semblance, then false speech must be possible; but false speech presupposes some mode of non-being in discourse, which Parmenides famously forbids. In Heidegger’s presentation, the early sequence of definitions (hunter, retailer, shopkeeper, disputant) is not a playful taxonomy; it functions as a controlled exhibition of how logos can be mobilized as a form of technē, as a “commerce” in sayings and convictions, until the sixth and seventh definitions (refuter, semblance-artist) precipitate the ontological crisis that compels a re-determination of non-being. The methodological narrative is summarized in the course and directly tied to the advance toward the problematic of mē on.
The critical hinge is the seventh definition. By analyzing mimētikē technē—and within it, the distinction of eikastikē (true image) and phantastikē (semblance)—Heidegger shows that Plato forces an acknowledgment of the “factual being” of images: the sophist’s craft is a poiein dokein legein, a making-seem in and by speech. This is not a moralistic denunciation of trickery; it is the controlled recognition that seeming is, that is, it has a determinate mode of presence and efficacy. From here the ontological question erupts: how can seeming be? The only way forward is to rethink non-being as heteron, the “other,” such that the “not” emerges as a positive, disclosive operator rather than as sheer absence. Here Heidegger insists on the seismic character of Plato’s innovation: a revolution in the concept of being signaled by the koinōnia tōn genōn (community of kinds) and the primacy of heteron among the “greatest kinds.” These are expositions Heidegger explicitly undertakes when he reaches the transition to the main ontological discussion.
The discussion of mē on begins with a renewed confrontation with Parmenides: the proscription of speaking of non-being is shown to rest on a construal of “saying” that cannot accommodate intentional directedness, combination, and separation. Heidegger unfolds the difficulty of “saying what is not” by analyzing what is meant in legein: there is always a peri hou (about-which), an hōs (as-which), and a hou (of-which). Falsehood and semblance belong structurally to this legein because logos is synthetic; it combines and separates in such a way that “not” can function as revealing otherness rather than destitution. Heidegger marks this step as Plato’s move beyond Parmenides, not by contradiction but by an ontological enrichment: the “not” is read out of heteron, which is one of the greatest kinds; non-being is thus the being-other with respect to a determinate region. The outline of this argument—its dependence on the genē and on koinōnia—is a fixed feature of the lecture’s middle movement.
Heidegger then broadens the field by surveying ancient theses about to on—unity, plurality—and contemporary positions in Plato’s milieu: ousia as body and ousia as eidos. The survey is not antiquarian; it is a staging of the two ways of encountering beings: aisthēsis (the visible, the causally accessible) and noein/logos (the intelligible in its participatory power). Heidegger stresses that both sides in the contemporary controversy tacitly presuppose “presence” as the guiding sense of being, which is precisely the soil from which Plato’s own answer grows: being as the parousia of power for communion, i.e., being as the capacity of the kinds to share in one another without collapsing into identity. This way of recasting being through dynamis koinōnias forms the bridge to the positive resolution via the greatest kinds, and Heidegger marks it as Plato’s original advance in ontological research, even while acknowledging Aristotelian motifs (the stress on archai and on dynamis) in Plato’s procedure. These connections, and the caution about Aristotle’s proximity and difference, are explicitly made in the course.
The positive resolution centers on the five “greatest kinds”: kinēsis, stasis, tauton, heteron, and to on. Heidegger’s guiding claim is that Plato’s analysis here is a fundamental dialectic, not a classificatory aside. The work has to show how these kinds communicate and how their communication grounds the possibility of knowledge and falsehood. In the decisive steps, heteron proves to be omnipresent across the kinds, such that every being is “other” than something; the “not” therefore names a structured relation (pros ti) rather than a nullity. This allows Heidegger to state—using Plato’s resources—that non-being has the full dignity of ousia as the being-other of what is in relation to determinate others. The sophist’s hiding place is thus ontologically illuminated: his product (phantasma) participates in being qua otherness, and false speech becomes thinkable without sacrificing the integrity of being. Although the course’s detailed unfolding of the five kinds exceeds what can be summarized, its decisive motifs—omnivariance of heteron, the “not” as disclosive, the synthetic structure of logos—are explicitly developed in the main part of the lectures.
A second transformation of the ground occurs when Heidegger returns from the “greatest kinds” to logos itself at Sophist 261c ff. If the koinōnia of kinds has been clarified, a new analysis of logos can proceed without logical prejudgments. Heidegger begins with names (onomata) and sayings (rhēmata), not to retrofit later grammar into Plato, but to show that “naming” and “saying” interlock as conditions for dēloun (making manifest). Names are not mere signs; they are intrinsically delotic, ways of letting something stand forth. Speech, as logos ti, always says something of something, structured by “about-which,” “as-which,” and “of-which.” Only by this articulation can falsehood arise: logos can “show” the other-than, i.e., present a thing as other than it is. Heidegger insists that Plato knows the distinction we later call noun/verb but does not yet inscribe it as such; Aristotle later grounds the grammatical noun in hypokeimenon and marks the verb by a temporal determination of presence, thus revealing how the ontological framework silently informs grammatical categories. These interpretive remarks and the warnings against retrojecting later grammar into Plato are stated plainly in the lecture’s analysis of logos.
It is crucial that logos is here no longer the unquestioned medium but the very topic: because saying can be idle, deceptive, or merely repetitive (as the Phaedrus critique of writing shows), it must be won back for truth by grounding it in dialectic—synagōgē and diairesis—that discerns the ways in which beings hang together and part company. Rhetoric becomes legitimate only as founded on dialectic; otherwise it remains a craft of conviction that refuses substance and institutionalizes opinion. Plato’s ambivalence toward rhetoric—negative in Gorgias, constructive in Phaedrus—is recorded in the course, and Heidegger uses it to exhibit the double valence of logos.
On this basis, the composition of the Sophist congeals into a single arc—only to be displaced by its own ontological discovery. The hunt’s diairetic method, at first a neat pedagogical apparatus for “finding the genus,” becomes pressed by its own success into the recognition that semblance-making is ontologically opaque unless non-being can “be” as heteron. The sixth definition (refuter) has already introduced elenchos as a purification of the soul from the worst ignorance—presumption that one knows—prefiguring the later exposition of falsehood; the seventh (semblance-artist) forces the question of image and phantasma into the center. As this arc tightens, the dialogue’s outer concern with distinguishing philosopher and sophist yields to the inner necessity of re-founding the “not” and of explicating how the greatest kinds communicate. The apparent shell (definitions) thus finds its kernel (being and non-being), and the kernel retroactively justifies the shell by showing that method only works because being itself is a field of communion and difference. This is Heidegger’s explicit reading of how the parts press into and replace one another as the dialogue advances. (The diairetic hunt, textually secured earlier in the course, becomes a subordinate moment once the koinōnia problematic has taken over.)
At this juncture, a methodological clarification is in order, and Heidegger provides it: dialectic is neither an eristic technique nor a mere propaedeutic to noein. It is the philosopher’s science because it uniquely thematizes how beings are accessible via logos, and because it alone can display the “history of provenance” of concrete beings by showing which kinds can and cannot commune. In this sense dialectic is freedom: the capacity to let beings be seen as they are by restraining the free-floating tendency of speech and restoring its service to disclosure. The course makes this point explicit when it defines dialectic as “journeying through logoi,” with synagōgē and diairesis as its constitutive moves, oriented by tauton and heteron.
From here, the lecture’s closing movement clarifies the structural stakes. First, the “extent and limit of logos”: speech is not “the” locus of truth, because truth occurs as noein (grasping) even without speech; yet only as apophansis (averring logos) does falsehood arise, since the synthetic structure of asserting enables the “not” to function. Hence the possibility of deception belongs to the same field that makes communication and science possible. Second, the rank of theoria is affirmed without abolishing practice: the priority of sophia is defended not on ethical grounds but ontological ones—because the being of beings in its highest sense is the measure of the truth-functions of our comportments—and yet this hierarchy is permanently exposed to the human tendency toward forgetfulness and idle talk, which demand constant dialectical vigilance. These theses are developed in Heidegger’s Aristotelian secunda pars and recalled in the transition to Plato.
A final compositional frame, not merely editorial, sustains the whole: the translatorial and archival scaffolding that transmits the course. The text we have integrates Greek citations and Heidegger’s paraphrastic renderings; the editors provide a glossary for Greek terms and interpolate German keywords where nuance would otherwise be lost. That the second half follows Moser’s transcript, authorized and annotated by Heidegger, is part of the book’s claim to fidelity; it also explains stylistic shifts between a more manuscript-driven first part and a transcript-driven second. This compositional history is stated in the framing matter and is essential for understanding why the lecture’s expository rhythm sometimes alternates between line-by-line running commentary and broader conceptual overviews.
Across these movements, the work’s method shows a consistent argumentative grammar. It begins from aletheuein as the lived execution of truth; it orients itself via Aristotle to focus Plato’s stakes; it makes a measured detour through Phaedrus to expose the duplicity of logos; it lets the “hunt for the sophist” push logos to the point where the ontological conditions of falsity must be explicated; and it resolves the crisis by articulating the koinōnia of the five greatest kinds such that the “not” is recognized as the operative mark of heteron. What Plato thereby achieves, in Heidegger’s account, is the possibility of speaking of non-being without contradiction, not by displacing being but by showing that being is intrinsically articulated as same and other, rest and motion, and that this articulation grounds both knowledge and the possibility of error.
The balance of textual security and inference should be kept distinct. It is textually secured that Heidegger installs a double preparation, adopts Aristotle as guide, and treats aletheuein as a mode of Dasein tied to logos. It is secured that he reads the early definition-sequence in the Sophist as a controlled preparation for the problem of non-being, and that he unfolds the koinōnia of the greatest kinds to determine mē on as otherness. It is secured that he analyzes logos at 261c ff. through onomata and rhēmata and warns against retrojecting full noun/verb grammar back into Plato, attributing the grammatical stabilization to Aristotle’s discovery of hypokeimenon and the temporal character of the verb. It is secured that he inserts the Phaedrus excursus to articulate rhetoric as psychagōgia when grounded in dialectic, together with Plato’s explicit suspicion of writing as a technology of seeming knowledge. It is secured, finally, that the transmission of the course rests on manuscript, student notes, and the authorized Moser transcript.
By contrast, it is an inference—though one licensed by the course’s emphases—that Heidegger treats the “hunt” as a methodological drama designed to teach the reader how to let being’s structures dictate method rather than the reverse. It is also inferential to say that the “kernel displaces the shell”: the text nowhere names this as a compositional law; the lecture’s pacing, however, makes it evident that once heteron has been won as the ontological sense of the “not,” the diairetic exercise retro-appears as an apprenticeship that has done its work. Similarly inferential is the claim that the alternation between close reading and conceptual overview mirrors the mixed textual basis (manuscript vs. transcript) and Heidegger’s practical concern to keep the philosophical rhythm of disclosure intact.
If one pulls these strands together, the book’s contribution can be clarified in closing. It repositions Sophist as a decisive laboratory for ontology: the possibility of falsehood becomes the wedge by which being and otherness are articulated together. “Otherness” is not a pale negation; it is the constitutive structure that allows discourse to say “not” in a way that reveals rather than annihilates. The sophist’s craft is thereby ontologically legible; he operates within an authentic region of being—the region where images and sayings can let-appear as other-than—and his threat to philosophy is commensurate with his proximity to it. The philosopher, by contrast, is the one who shoulders the dialectical labor of distinguishing and gathering in such a way that logos is reclaimed for truth, and that the mobility of speech no longer floats free of the things but becomes the organ of their manifestation. The lecture course secures this outcome by its double preparation, exercises it across Aristotle and Plato, and preserves it by making the koinōnia of the kinds the decisive ontological insight to which the dialogue was always tending. In this sense the work not only bridges “ancient and modern” concerns; it reopens the standing task of philosophy: to think the intimacy of truth and language such that semblance is neither banished as mere illusion nor enthroned as sovereign power, but understood as a mode of being that demands, and can receive, a rigorous account.
Simon Gros 
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