Martin Heidegger did his major study lecture course on Plato’s Sophist around the same time as Being and Time, and a major focus is Antisthenes on the question of naming. Let’s approach this obliquely with the question on the sciences.

Academic fields differ in their objects of inquiry based on the nature of reality they address—empirical vs. abstract, individual vs. collective, temporal vs. eternal. Below is a comparative overview of key fields, highlighting typical objects and their distinctive characteristics. I’ve selected representative areas (psychology, history, natural sciences) and others for breadth (e.g., social sciences, humanities, mathematics, philosophy itself).

Academic Area	Typical Objects of Inquiry	Key Characteristics
Psychology	Mental processes, behaviors, emotions, cognition, personality traits, disorders.	Subjective and internal; influenced by individual experiences and biology; often intangible and variable (e.g., affected by context or culture); empirical but reliant on self-reporting or indirect measures (e.g., experiments, surveys); dynamic and probabilistic rather than deterministic.
History	Past events, societies, cultures, artifacts, documents, figures, and narratives.	Temporal and contextual; reliant on incomplete evidence (e.g., archives, relics); interpretive and narrative-driven; subject to bias and revisionism; focuses on causality, contingency, and human agency over time; not repeatable or experimental.
Natural Sciences (e.g., Physics, Chemistry, Biology)	Physical phenomena, matter, energy, laws of nature, organisms, ecosystems.	Objective and empirical; governed by universal laws (e.g., gravity, evolution); measurable and quantifiable; testable via experiments and falsification; often reductionist (breaking down to fundamental parts); predictable and replicable under controlled conditions.
Social Sciences (e.g., Sociology, Economics, Anthropology)	Social structures, institutions, human interactions, economies, cultures.	Collective and relational; influenced by power dynamics, norms, and environments; empirical but interpretive (e.g., qualitative ethnographies or quantitative models); variable due to human agency and unpredictability; often normative (involving values like equity).
Humanities (e.g., Literature, Art History, Linguistics)	Texts, artworks, languages, cultural expressions, ideas.	Symbolic and interpretive; focused on meaning, aesthetics, and human experience; subjective and hermeneutic (involving interpretation loops); timeless yet context-bound; emphasizes creativity, critique, and ethical dimensions over empirical proof.
Mathematics	Abstract structures, numbers, geometries, proofs, algorithms.	Formal and logical; eternal and a priori (independent of empirical reality); deductive and axiomatic; precise and universal; focuses on patterns, relations, and consistency; not falsifiable in the empirical sense but provable or disprovable via logic.
Philosophy	Concepts like existence, knowledge, ethics, reality, mind-body relations.	Abstract and foundational; reflexive (inquiry about inquiry itself); dialectical and argumentative; open-ended and speculative; integrates traits from other fields but prioritizes reasoning over evidence; often deals with universals and paradoxes.
Engineering/Applied Sciences	Systems, technologies, processes, designs for practical problems.	Practical and goal-oriented; combines empirical data with innovation; iterative and prototype-based; constrained by real-world feasibility (e.g., materials, ethics); focuses on optimization, efficiency, and application rather than pure discovery.

These characteristics are not exhaustive or mutually exclusive—fields often overlap (e.g., cognitive psychology draws from natural sciences). The choice of object shapes the discipline’s methods: empirical fields prioritize observation and experimentation, while abstract ones emphasize logic and interpretation.

Now, Philosophy is not just going to be a specific area of inquiry thought as its most foundational (e.g., philosophy of physics), but what traits belong to an object of inquiry as such: the object of inquiry in general. This is not a specific area but a prior hermeneutic projection/context within which a specific object of inquiry (like historical entities) makes sense.

Philosophical Traits of an Object of Inquiry in General

Philosophically, an “object of inquiry” refers to any entity, phenomenon, concept, or relation that becomes the focus of systematic investigation within a field of knowledge. Drawing from traditions in epistemology (the study of knowledge) and ontology (the study of being), such objects share several core traits:

• Accessibility to Investigation: It must be amenable to observation, analysis, or reasoning, whether through empirical methods (e.g., sensory data) or rational deduction (e.g., logical inference). This aligns with Kantian ideas of phenomena (things as they appear) versus noumena (things in themselves), where inquiry targets the former.
• Definability and Boundaries: It possesses identifiable properties or attributes that allow it to be delimited from other objects, enabling categorization, hypothesis formation, and testing. In Aristotelian terms, it has an essence or form that can be grasped intellectually.
• Relationality: It exists in relation to other entities, contexts, or observers, often involving causality, temporality, or interdependence. For instance, in Hegelian dialectics, objects of inquiry evolve through thesis-antithesis-synthesis, reflecting dynamic interactions.
• Uncertainty or Problematic Nature: It inherently poses questions, gaps in understanding, or paradoxes that drive inquiry, as per Popper’s falsifiability principle—true objects of scientific inquiry must be refutable.
• Context-Dependence: Its traits are shaped by the inquirer’s framework (e.g., cultural, methodological), echoing Kuhn’s paradigm shifts where objects are reinterpreted across scientific revolutions.
• Potential for Knowledge Generation: It yields insights that contribute to broader theories, laws, or narratives, transforming raw data into structured understanding.

These traits are universal but manifest differently across disciplines, influenced by the field’s ontology (what exists), epistemology (how we know), and methodology (how we investigate).

Plato’s Sophist

Now let’s get a little more philosophical and ask what makes naming an object of inquiry possible (e.g., labelling something as depression in psychological inquiry). In Plato’s critique of Antisthenes in the Sophist, what are the categories we presuppose (e.g., being, in itself, etc) even when we are merely naming something? I encounter the dog “as” not me, for instance?

In Plato’s Sophist, the critique targets a group referred to as the “late-learners” (sometimes translated as “late students” or “those who learn late in life”), whom scholars widely identify with Antisthenes and his followers, or possibly related Megarian or Eristic thinkers. These figures are portrayed as holding a rigid ontological and semantic position that denies the possibility of non-identical predication—meaning you cannot attribute one property or name to another thing without violating fundamental principles of unity and multiplicity. For instance, they insist that statements like “man is good” are invalid because they would make “the one many and the many one,” treating kinds (or forms) as utterly isolated and incommunicable. Only tautological identities (mere naming), such as “man is man” or “good is good,” are permissible, as anything else implies an illegitimate combination of distinct entities.

Through the character of the Eleatic Stranger (conversing with Theaetetus), Plato refutes this by demonstrating that even the late-learners’ own assertions and the act of naming or speaking presuppose the interweaving or “communion” (koinonia) of certain fundamental categories or “kinds” (gene). Denying all combination leads to absurdity, as it would render discourse, reasoning, and even falsehood impossible—since statements require linking subjects to predicates: something “as” something else: the plant “as” green; “as” it is in itself, etc.

Plato uses an analogy with letters (some vowels allow consonants to combine into syllables) to illustrate that not all kinds mix with all others, but some must mix selectively to enable meaningful speech.

Plato argues that even “merely naming something” (e.g., calling an object “dog” or referring to it in isolation) implicitly relies on core ontological categories, as naming distinguishes, identifies, and asserts existence in ways that demand their interplay. These are not arbitrary but are among the “greatest kinds” (megista gene) that permeate all reality and discourse. The five greatest kinds outlined in the dialogue are Being, Motion, Rest, Sameness, and Difference (also called “Other”). However, the ones most directly presupposed in mere naming or basic predication—even in the late-learners’ tautologies—are Being, Sameness, and Difference, as they function like “vowels” enabling all combinations.

Motion and Rest serve as examples of kinds that do not combine with each other (motion is not rest) but both participate in the other three. Here’s a breakdown of these presupposed categories, with their roles in naming:

• Being: Any act of naming asserts that the thing “is” or exists in some way. Even saying “man is man” combines the subject with existence, presupposing participation in Being. Without this, no entity could be referred to at all, as naming implies attributing “is” (existence or essence) to it. Plato notes that Being interpenetrates with other kinds, allowing things to “be” while also being “not” in certain respects.
• Sameness (or Identity): Naming identifies the thing as “the same as itself” (e.g., the dog is this dog, not dissolving into multiplicity). This is implicit in any reference, as it maintains the unity of the named entity across contexts. The late-learners’ tautologies rely on this, but Plato shows it’s a distinct kind that combines with others (e.g., “motion is the same [as itself]” but also partakes of Being).
• Difference (or Other): To name something is to distinguish it from everything else—it’s “not” other things. The example above of encountering the dog “as not me” directly invokes this: the dog is perceived or named “as” other than yourself, presupposing Difference as a pervasive kind that enables negation and distinction without implying absolute non-existence. Plato reframes “not-being” not as sheer nothingness but as participation in Difference relative to Being (e.g., “not-me” means other than me, yet still a being).
• In Itself (related to Rest or Unity): While not always listed separately, “in itself” ties to Rest (as opposed to Motion), which Plato uses to show isolation isn’t absolute—Rest partakes of Being, Sameness, and Difference but not Motion. Naming something “in itself” presupposes this stability, but even here, it combines with the core trio to avoid total separation.

In essence, Plato’s point is that the late-learners contradict themselves: their denial of combination still employs these categories in their speech (e.g., using “is,” “apart,” or “from others”). This critique paves the way for resolving puzzles about falsehood and not-being, showing that reality involves selective communion of kinds, making predication and naming possible.

APPLICATION

Plato’s discussion in the Sophist—particularly the critique of the “late-learners” (associated with Antisthenes) and the identification of fundamental categories like Being, Sameness, Difference, Motion, and Rest—provides a foundational ontology for how any naming or predication works. When we extend this to designating something as an “object of psychological inquiry” (e.g., naming “anxiety,” “cognition,” or “behavior” as such), these categories are implicitly presupposed. Without their interplay (or “communion”), we couldn’t coherently isolate, describe, or investigate psychological phenomena as distinct objects of study. Below, I’ll explain this step by step, integrating the philosophical traits of objects of inquiry in general (e.g., accessibility, definability, relationality) with the specific characteristics of psychological objects (subjective, internal, variable, context-dependent).

1. Recap: Plato’s Categories in Naming from the Sophist

In the Sophist, Plato argues that even “merely naming” something—without full predication—relies on core “greatest kinds” that must combine selectively, like vowels enabling syllables. The late-learners’ error is insisting on absolute isolation (only tautologies like “dog is dog” are valid), but this overlooks how naming inherently involves:

• Being: Asserting existence or “is-ness.”
• Sameness: Unity and self-identity.
• Difference (Other): Distinction via negation (“not” other things).
• Motion and Rest: As examples of kinds that don’t mix with each other but partake in the above, illustrating dynamic vs. static aspects.

Naming isn’t neutral; it presupposes these to avoid reducing everything to incommunicable unity or chaotic multiplicity. For instance, encountering a dog “as not me” invokes Difference relative to Being, allowing distinction without annihilation.

2. Characteristics of a Psychological Object of Inquiry

Psychological objects (e.g., emotions, thoughts, mental disorders) are:

• Subjective and Internal: Not directly observable like physical objects; they involve personal experience.
• Variable and Dynamic: Changeable, influenced by context, biology, and culture.
• Relational: Tied to the self, others, and environments; often probabilistic.
• Accessible via Indirect Methods: Through self-reports, experiments, or inference, but always interpretive.

Philosophically, any object of inquiry must be definable, relational, and knowledge-generating. Psychological ones add a layer of introspection and temporality, making them inherently “in motion” (e.g., a thought evolves) yet requiring stability for study.

3. How Plato’s Categories Are Presupposed in Naming a Psychological Object

When we name something as a “psychological object of inquiry”—say, labeling “depression” as a mental state worthy of study—we aren’t just applying a tag; we’re engaging in an act of ontological commitment that presupposes Plato’s categories. This enables the object’s accessibility and definability, bridging the gap between mere naming and full inquiry. Here’s how each category plays out:

• Being: Naming “depression” as psychological asserts its existence as a real phenomenon (it “is”). Without presupposing Being, we couldn’t treat it as an object at all—it would dissolve into non-existence. In psychological inquiry, this allows us to say “depression exists as a cluster of symptoms,” making it accessible to empirical study (e.g., via DSM criteria). Philosophically, this ties to the general trait of uncertainty: depression poses problems (e.g., causes?) because it “is” yet elusive.
• Sameness: The object must be identified as unified and self-identical (“depression is depression,” not fracturing into unrelated parts). This presupposes Sameness to maintain boundaries, preventing the late-learners’ trap of isolation. For psychological objects, which are variable, Sameness provides the stability needed for categorization (e.g., distinguishing clinical depression from transient sadness). It enables relationality in inquiry: we can compare instances across individuals while preserving the object’s core essence.
• Difference: Crucially, naming it “as psychological” distinguishes it from non-psychological things—it’s “not” a physical ailment like a broken bone, “not” a historical event, “not” me in toto (though it may affect me). This echoes our dog example: we encounter a mental state “as not” external reality, invoking Difference to delimit it. Without this, psychological inquiry couldn’t isolate internal phenomena from, say, natural sciences objects (e.g., brain chemistry as biological vs. experiential). It supports the subjective trait: depression is “other” than observable matter, allowing interpretive methods over strict quantification.
• Motion and Rest (with Communion): Psychological objects are dynamic—emotions shift (Motion)—yet must have moments of stability (Rest) for analysis (e.g., a fixed diagnosis). Plato shows these don’t combine directly (motion isn’t rest), but both partake in Being, Sameness, and Difference. Naming a psychological object presupposes this selective mixing: without it, we couldn’t predicate change (e.g., “anxiety increases under stress”) or investigate causality. This aligns with the problematic nature of inquiry objects—psychological ones drive questions because they’re in flux, yet nameable.

In sum, Plato’s framework reveals that naming a psychological object isn’t a simple act but a presupposition-laden one that “weaves” these categories to make inquiry possible. The late-learners’ denial would render psychology incoherent: no predication means no statements like “behavior is influenced by cognition,” collapsing the field into tautological silos. Instead, communion allows the relational, context-dependent traits of psychological objects to emerge, generating knowledge (e.g., therapies). This extends to other fields—e.g., historical objects presuppose temporality (Motion) differentiated from the present—but psychology uniquely highlights subjectivity through Difference from the external.

So, that’s good background/context for approaching Derrida’s essay “Sauf le nom,” which I will begin with next time!