Category (philosophy)

from Wikipedia, the free encyclopedia

Under categories ( Greek κατηγορία kategoria u. A., Indictment ', later, property', 'statement' or ' predicate ') is understood in the logic basic concepts within the ontology and metaphysics basic features of the beings . Since the verb kategorein translates into Latin praedicare , categories are also called predicaments, especially in the Middle Ages . With Kant, categories are a priori forms of thought and thus the basic requirement for all experiences. In the 20th century, the categories are understood and developed as open conceptual systems for structuring the world that can be experienced. Philosophical categories are absolute in that they cannot be traced back to other more general concepts. All sciences have their category structure. In physics such categories are e.g. B. the seven basic sizes .


The basic problem of the categories is that of the order and hierarchy of beings . Following the Parmenidean and Heraklitic thinking, Plato focuses on the question of what beings are and what kind of being they are . So the question is what it actually means when we say something “is”. This question, which is unusual for everyday thinking, turns out to be one of the most difficult basic questions in philosophy or ontology .

When questioned consistently, we found that the little-reflected everyday statements about the world and its character are often impossible to keep if you think about it more closely. But since, despite all the philosophical uncertainty about the final questions, we can gain knowledge of facts and circumstances, he has Socrates ask the question of the structures of our knowledge in his Platonic dialogues . It is noticeable that despite all the diversity of things and facts, we can apparently grasp something general and identical within the world.

For Plato, the basis for this ability is the participation in unchangeable ideas , which are to be understood as templates for the individual, concrete things that these are “copied”. For example, a concrete table takes part in the idea of ​​a table or a 'table-like feel' and is modeled on this idea by the hand of the carpenter. The concept of idea is derived from the Greek word idein , see, as a noun. But the ideas can only be known through thinking.

In the dialogue of Sophistes , Plato introduces five main genres or meta-ideas. In terms of content, these cannot be linked to other terms and therefore represent the original principles of being because they cannot be traced back to others. In this dialogue he developed the first category structure for describing being in ancient philosophy. These concepts are beings, rest and movement, as well as sameness and difference. The community of these concepts lies in their share in being, while they are completely different from one another. None of the terms is contained in another.


Aristotle largely follows Plato, but he gives the term ousia ( essence , substance ) a special meaning. In Phaedo , Plato said about ousia that it is what every being is as itself (Phaedo 65d-e; 75d). Aristotle adopts this definition of characteristics, but he intensifies its meaning: the question of what is all essence? , by which the individual essence of a thing is meant, turns to the fundamental philosophical question according to Aristotle: What is the essence itself?

Aristotle is considered to be the founder of the "theory of categories" in the narrower sense, which is dealt with in the text The Categories (whose title, however, does not come from Aristotle himself). Here (Cat. 4, 1b 25) Aristotle distinguishes between ten categories (in brackets first the Greek expression in italics, then the examples given by Aristotle at this point):

  1. Substance ( ousia , a person, horse),
  2. Quantity ( poson , a two (three) ells long),
  3. Quality ( poion , a white, a grammar knowledgeable),
  4. Relation ( pros ti , a double, a half, bigger),
  5. Where ( pou , in the market, in the lyceum),
  6. When ( pote , yesterday, last year),
  7. Location ( keisthai , he lies, sits),
  8. Have ( eh , he's shod, armed),
  9. Do ( poiein , he cuts, burns),
  10. Suffering ( paschein , it is cut, burned).

Aristotle mentions the same categories (but without examples) in Top. I 9 (103b 20). In other places Aristotle lists fewer categories ( Analyt. Post. I 22, 83a 21; 83b 16; Phys. V 1, 225b 6, Met. V 7, 1017a 24ff).

Aristotle contrasts the first category, the substance, with the rest, the accidents (e.g. in Analyt. Post. I 22, 83a 25). This distinction arises from the fact that the substance exists independently , while the accidents can only exist with one substance. For example, Socrates can exist without his beard, but the beard cannot exist without Socrates. This makes it possible to explain why, for example, a person who changes over time, i.e. experiences accidental changes, nevertheless remains essentially the same person. So Socrates can take off his beard and still remain Socrates.

Within the substance, Aristotle again differentiates between the first and second substance (cf. Cat. 5, 2a 25). The first substance is the individual , e.g. B. Socrates, the second substance is the type of the individual, e.g. B. Human. In the Middle Ages, the relationship between the individual and the species was discussed in the universal dispute: The question here is whether species also exist independently of individuals.

Significant comments on Aristotle wrote a. a.

For a long time the writing Categoriae decem , also called Paraphrasis Themistiana , was important for the transmission , a Latin summary of the category writing of Aristotle.


While Aristotle had investigated the way in which statements about something existent are possible, the interest of the Stoics was directed to finding classifications for real objects. They therefore differentiated - first attested in Chrysippus by Soli - four "genera of beings": the substrate as the substance that underlies all things as substance ( hypokeimenon ), the property bound to the substrate that belongs to the essence of the individual thing and is in it becomes concrete (Poion), the self-behavior linked to the respective situation (Pos echon) as well as properties that only result from the relation to other self-behavior, such as father and son or right and left or the mutually supporting stones of an archway ( Pros ti pos echon). As with all other philosophical directions, the categories and their relationship to one another are here also an expression of the inner order of the cosmos.

Thomas Aquinas

Thomas Aquinas , too, differentiates between substance and accident and thus, like medieval philosophy in general , stands in the tradition of Aristotle. In addition, the connection between philosophy and theology is a central aspect for Thomas .

In this context, the divine comes into focus. How should the divine being be understood under the ideas of Aristotle? Aristotle himself spoke of an "unmoving mover", which, however, contradicts Christian revelation with its personalized image of God. Thomas is therefore faced with the task of uniting the Christian conception of God with the ontological concepts of Aristotle and reconciling them with one another. Central terms here are essence and being , possible and real, as well as form and matter .

Ultimately, Thomas has to show in which form God stands out from all other being and how this can be thought without contradiction within the Aristotelian thinking, to which Thomas tries to remain faithful. The pair of terms “possibility” and “reality” may be an example of this approach. Every individual has, in the spirit of Aristotle, " essence ", i. H. Essence, and existence , d. H. To be there. Whether the essence is realized in existence is part of the realization of possibilities. The observation of nature corresponds to this picture: a seed has the potential to become a plant.

For the being of God it must now be possible to think that He is not subject to this restriction. Only in God, according to Thomas, is there the aspect of reality alone: ​​God is the pure act . God is the only being in which there is no possibility whatsoever (neither with regard to existence nor with regard to being). Realization is found in God without it having emerged from a potentiality of the being.

Immanuel Kant

Chalkboard of the categories.
1. The quantity :
Allness .
2. The quality:
Limitation .
3. The relation :
of inherence and subsistence ( substantia et accidens )
of causality and dependency (cause and effect)
the community ( interaction between the doer and the sufferer).
4. The modality :
Possibility - impossibility
Existence - non-existence
Necessity - randomness .
Immanuel Kant: AA III, 93– KrV B 106

According to Kant, categories are a priori and immediately given. They are tools of judgment and tools of thought. As such, they are for application only and have no existence. So they exist only in the human mind. You are not tied to experience. Because of their immediacy, they are not tied to signs either. Kant's epistemological goal is to provide information about the conditions of the validity of judgments. Without this information, many judgments can be made, but they must then be called "systematic doctrine (s)". Kant thus criticizes the purely analytical thinking of science as wrong and contrasts it with the necessity of synthesizing thinking. Kant founds the validity with the transcendental subject . The transcendental subject is a pure reflection concept, which represents the synthesizing third (as in later philosophies spirit (Hegel), will, power, language and value (Marx)) that cannot be perceived by the senses. Here Kant seeks the answer to the question of how man can be constituted as a rational being, not in analysis but in a synthesis.

For Immanuel Kant , which thus is considered an important innovator of "pre-critical" by then doctrine of categories, there are twelve "Categories of Pure Reason". For Kant these categories are concepts of the understanding , but not expressions of the actual being of things in themselves . With this, the ontological view of tradition changes into an epistemological view, which is why Kant's “critical” philosophy (since the Critique of Pure Reason ) is often referred to as the “ Copernican turn in philosophy”.

Quantity , quality , relation and modality are the four basic judgment functions of the mind according to which the categories are formed. Accordingly, z. For example, the judgment function “quantity” subordinates the categories or judgments “unity”, “multiplicity” and “allness”, and the judgment function “relation” the judgments of “cause” and “effect”.

Friedrich Adolf Trendelenburg already mentions the widespread criticism that Kant did not systematically derive the forms of judgment on which the categories are based and thus justify them as necessary. One of the points of criticism is that the categories refer partly to views (individuality, reality, existence), partly to abstractions such as summarizing, limiting or justifying (multiplicity, allness, negation, limitation, possibility, necessity).

Charles S. Peirce

For Charles S. Peirce , the question of categories was an essential starting point of his philosophy. Peirce developed a theory of categories, which are not like Kant with the types of knowledge , but with modes of being involved and the basis of his theory of signs forms. Peirce's categories cannot be described with logic, but can only be examined phenomenologically. They are contained in every phenomenon and are therefore universal. Conceptually, Peirce differentiated purely formal first , second and third as forms in which everything that is is reflected:

  • "Primacy is the way something would exist for itself, unrelated to anything else, so that it would make no difference if nothing else existed, or ever existed, or could exist." Primacy is the being of something unrelated on something else. It is being in itself that exists as a pure possibility (e.g. redness as a possibility);
  • “A second can be defined as a change in the being of an object, which ipso facto is a mode of being of an object that is clearly different from the first. Or more precisely, secondness is that in each of two absolutely separate and distant objects, which assigns each of them to the other, not for my mind or for or through any other mediated object or mediated circumstance of whatever kind, but in these two Objects alone, so that it would behave in the same way if nothing else existed or ever existed or could exist. " Second is the determination of what is here and now of something (the opposition of two as yet unreflected feelings);
  • “The idea of ​​thirdness is the change in the being of an object, which is a mode of appearance of a second, in so far as it is the change of a third. You could call it an inherent reason. " Third is the principle behind things, the regularity associated with the phenomenon (e.g. that a door is to be opened, that a table has a shelf, the algorithm of the computer program) .

A connection to the Kantian categories arises again when Peirce sets possibility = first, actuality = second and necessity = third. The situation is similar with the relations quality (1), fact (2) and behavior or law (3) as well as with the terms object (1), relation (2) and representation (3). The triad was for Peirce a fundamental perspective on all the phenomena, and he looked even in the Christian Trinity confirmed. Although the categories can be conceptually differentiated, they cannot be separated. They are all contained in every thought and can only be grasped with clarity in a long process of appropriation. Accordingly, there are repeatedly texts from Peirce with different approaches to the categories.

Wilhelm Dilthey

Wilhelm Dilthey , as one of the founders of the philosophy of life, established life as the undeniable basic fact of philosophizing. Man's life is always a history-bound flow in the time in which man experiences his world. In this experience, three categories of thinking are decisive for man, namely values, purposes and meanings, which are linked to one another through the dimension of time:

“By looking back in memory, we grasp the context of the expired links in the course of life under the category of meaning. When we live in the present, which is filled with realities, we experience in feeling its positive or negative 'worth, and as we reach towards the future, the category of purpose arises from this behavior. We interpret life as the realization of a supreme purpose to which all individual purposes are subordinated, as the realization of a highest good. None of these categories can be subordinated to the other, since each makes the whole of life accessible to understanding from a different point of view. "

Overall, Dilthey wrote its own category theory (The Categories of Life), which was published from the estate, and in which Dilthey differentiated between formal and real categories. The formal categories are "based on reason as such, [...] through which thinking illuminates reality." [...] "There is no universality outside, but there are only facts that thinking fits into them and thus itself clarifies. ”This type includes terms such as order, relationship, identity, equality or difference. In contrast, the real categories are life categories that are taken from the real life context. Because life as a whole cannot be grasped by concepts, there is also no way of defining the categories of life conclusively. “The context of life and its structure is one, it is alive, yes, life itself. It cannot be fathomed through concepts. Therefore, no attempt has ever been made to determine the nature, number and order of these categories. "

Dilthey names selfhood, work and suffering as well as categories that describe the essence as the relevant categories of life. Dilthey uses self-equality to describe the immediate certainty that “in a life unit a unit that can only be experienced and cannot be expressed by any concept holds together everything that is different and all changes.” Self-equality is given by the inner experience of the self and the basis for the fact that there is a you, that Concepts of how thing, reality or substance are formed. Working and suffering is the interaction of the directly experienced will, the will-shaped forces of the outside world, which children or primitive peoples, for example, perceive to a particular degree. Only in a culturally developed world are these terms transformed into ideas of cause and effect or the abstract law of causality. Finally, the third group of categories is that in which terms such as “essentiality or essence, purpose, value, sense, meaning” are recorded. In these categories lies what constitutes the focus of every person. In them are the meaning and purpose of life. Categories such as value, utility, purpose and means are derived from them. “Just as substance and causality arise from living roots, but then take on an abstract form in the context of knowledge, the same development also takes place from these concepts. And this is how the categories of essence or essentiality arise. "

Alfred North Whitehead

A scheme of categories also forms the basis of the work Process and Reality by Alfred North Whitehead . This uses the categories as basic definitions and sentences of a systematic metaphysical theory, similar to the structure of scientific theories. The purpose of this approach is to check the conceptual coherence of his metaphysics, but also to be able to apply his theory to scientific research results. Coherent means that there must be no individual events in the experience that contradict the general ideas (= categories) or even just outside the inner context of the theory. Categories are therefore generally valid terms and fundamental statements that define the framework for the development of a theory.

Overview of the category scheme by Alfred North Whitehead

The highest level, which in Whitehead has a similar position as in Aristotle the substance, is the " category of the ultimate " (PR 63). Becoming is a dynamic process in which new things are constantly being created. That is why the elementary category contains the moment of creativity . This is the "universality of all universals" because it is contained as a principle, as an inner stimulating force, as a constitutive quality in all elements of nature. The question of unity and diversity is also elementary. Unity stands for the one, the identity and singularity of individual process elements (Whitehead's term: real individual beings), which in their multiplicity must, however, always be thought of as interconnected. Unity and diversity presuppose one another. In logic they have their equivalent in the analysis of the relation between part and whole. The ultimate individual is a multidimensional, infinite division of the whole of reality. Creativity means that in the process of becoming a new unity arises from a multitude of elements. This clearly shows Whitehead's Platonism . Thus it says in Parmenides (156 from): “The one then, as it seems, since it grasps being and lets it go, it also becomes and passes away [...] Since it is now one and becomes much and becoming and passing away not when it becomes one, the being-many pass, but when it becomes much, the being-one pass? "

Whitehead divided the category of the elemental into three categories of existence, explanation, and liability. Categories of existence, as the class of beings, name the basic elements of reality. Above all, this includes the real individual beings or real events, relations or information, connections (nexus), forms, contrasts and timeless objects as pure potentials. Explanatory categories are used to describe natural events. Whitehead listed what constitutes a process in 27 explanatory statements. The nine categories of liabilities relate to the subjective internal perspective. They describe the conditions, the range of possibilities under which a process can take place.

“Every individual should be a specific case of a category of existence, every explanation a specific case of categories of explanation, and every condition a specific case of categorical obligations. The category of the elementary formulates the general principle that is presupposed in the three more specific category tables. "(PR 61)

Nicolai Hartmann

In his work “The Structure of the Real World”, Nicolai Hartmann developed a general theory of categories based on the layered structure of beings.

He divided real being into the ascending layers of inorganic, life, soul and spirit. Each layer builds on the next level. Fundamental and specific categories apply to each layer. The fundamental categories consist of pairs of opposites (AdrW, 230). They are elementary and cannot be traced back to others.

List of fundamental categories
  • Principle and Concretum
  • Structure and mode
  • Form and matter
  • Inside and outside
  • Determination and Dependency
  • Unity and Diversity
  • Unanimity and conflict
  • Opposition and dimension
  • Discretion and continuity
  • Substrate and relation
  • Element and structure

Hartmann emphasized that his categories - unlike Aristotle and Kant - are not determined according to a uniform principle. However, they have the fundamental property that from each pair the other pairs can be derived gradually. As a result, the categories each depict one aspect of a uniform context (AdrW, 255). The pairs of categories are internally related and externally related to one another. The content of the categories is different in the individual layers. Determination is to be interpreted as physical causality on the level of the inorganic, on the level of life as drive, in the soul as motive and in the spiritual as reason.

In the third part of "Structure of the Real World" Hartmann established categorical laws:

  1. Categories are firmly connected with the concrete.
  2. Categories are conditioned within a category layer.
  3. Categories from the higher tier contain many of the categories from the lower tier, but in a modified form.
  4. Higher strata depend on the lower, but not vice versa.

If one looks at the connection between strata and categories, Hartmann believes that many worldviews contain the fundamental error of fundamental one-sidedness.

  • The materialism attempts to derive organic, emotional and mental phenomena of physical processes and provides for the more complex structures on top of each higher level.
  • Similarly, biologism tries to establish the soul and spirit from the principles of life and overlooks the laws of novelty and freedom (AdrW, 498)
  • The vitalism tries to explain the principle of finality , although this is a category of mind.
  • In idealism , the world is explained on the basis of the principle of the subject , although the subject is to be assigned to the level of the spirit.

Analytical philosophy

Modern analytical ontology formulates theories of the basic categories, things, properties, events, parts and wholes in terms of the logical form of language. While Rudolf Carnap wanted to separate categorical existential questions from so-called “internal” existential questions within a linguistic framework and dismissed the categorical ones as pseudo-problems, Willard Van Orman Quine attacked this distinction and instead advocated a theory of the “ontological commitment” of a theory to a certain object area. The focus is on how the various categories relate logically to one another and whether certain categories can be reduced to others . Central terms here are entities , universals , individual things , properties, facts and tropes (numerically identical instances of properties). Reinhardt Grossmann, for example, describes categories as “types of abstract things” and gives a list of seven such types: individuals, properties, relationships, structures, sets, quantifiers and facts.

Special category theory

The philosophical theory of categories deals primarily with the general categories that are regarded as valid for many or all areas of knowledge. In addition, approaches to "regional category theory" have emerged, especially since category-analytical studies here require the corresponding specialist knowledge of the relevant areas. Thinking about suitable categories and category errors is particularly important for biology and even more so for psychology . To what extent can life phenomena be traced back to elementary categories and laws of organic chemistry and physics? Can the consciousness and behavior of people be accurately and completely (adequately) captured in the categories of neurophysiology or the social sciences ? (see Explication of Terms)

Other authors on category theory

See also


Primary literature
  • Klaus Oehler : Aristotle. Categories, translated and explained. Berlin 1984
  • Nicolai Hartmann: The structure of the real world: outline of the general theory of categories. Berlin 1940.
  • Immanuel Kant: Critique of Pure Reason . with a detailed bibliography by Heiner Klemme. Meiner, Hamburg 1998, ISBN 3-7873-1319-2 .
  • Charles S. Peirce: The Thought and Logic of the Universe. The Lectures of the Cambridge Conferences of 1898. Ed. By Kenneth Laine Ketner. Suhrkamp, ​​Frankfurt 2002, ISBN 3-518-58325-5 .
  • George Lakoff: Women, Fire, and Dangerous Things - What Categories Reveal about the Mind. The University of Chicago Press, 1987, ISBN 0-226-46803-8 .
Secondary literature
  • Hans-Michael Baumgartner, Gerd Gerhardt, Klaus Konhardt, Gerhard Schönrich: Category, category theory . In: Joachim Ritter et al. (Ed.). Historical dictionary of philosophy. Volume 4. Wissenschaftliche Buchgesellschaft, Darmstadt 1976, pp. 714-776.
  • Wolfgang Carl: The Transcendental Deduction of the Categories in the first edition of the Critique of Pure Reason. A comment. Klostermann, Frankfurt am Main 1992, ISBN 3-465-02532-6 .
  • Johannes Heinrichs: The logic of the critique of reason , Francke UTB, Tübingen 1986; New edition: The secret of the categories. The decryption of Kant's central teaching piece , Maas, Berlin 2004. ISBN 3-929010-94-1 .
  • Thomas Hünefeldt: Peirce's deconstruction of the transcendental philosophy into a phenomenological semiotics. Königshausen & Neumann, Würzburg 2002, ISBN 3-8260-2197-5 .
  • Dietmar Koch, Klaus Bort (Ed.): Category and categoricality. Historical-systematic research on the concept of the category in philosophical thought. Festschrift for Klaus Hartmann on his 65th birthday. Königshausen & Neumann, Würzburg 1990, ISBN 3-88479-513-9 .

Web links

Individual evidence

  1. ^ Gernot Böhme: Plato's theoretical philosophy , Metzler license edition, Scientific Book Society, Stuttgart 2000, p. 9.
  2. Plato. Sophistes. Text and commentary by Christian Iber, Frankfurt 2007, 289.
  3. Max Pohlenz: The Stoa. History of a movement. Vandenhoeck & Rupprecht [1959]. (7th edition. Göttingen 2009, pp. 69-70).
  4. Immanuel Kant, Collected Writings. Ed .: Vol. 1-22 Prussian Academy of Sciences, Vol. 23 German Academy of Sciences in Berlin, from Vol. 24 Academy of Sciences in Göttingen, Berlin 1900ff., AA III, 93– KrV B 106 .
  5. See Kant-Lexikon, Eisler [1]
  6. Cf. §59 Critique of Judgment of 1790 and on signs of fundamental cf. Section 36 Anthropology in a pragmatic way from 1798.
  7. KrV tr. Anal. 2. B. 3. H. I 278-Rc 341 f. See [2] .
  8. See Kant-Lexikon, Eisler [3] .
  9. See Kant-Lexikon, Eisler [4] .
  10. See Kant-Lexikon, Eisler [5] .
  11. ^ Friedrich Adolf Trendelenburg: Logical investigations, Volume 1, 3rd edition. 1870, 333-334.
  12. Charles S. Peirce: The Thought and Logic of the Universe. The Cambridge Conferences Lectures of 1898 , ed. By Kenneth Laine Ketner, Suhrkamp, ​​Frankfurt 2002, 200.
  13. Charles S. Peirce: The Thought and Logic of the Universe. The Cambridge Conferences Lectures of 1898 , ed. By Kenneth Laine Ketner, Suhrkamp, ​​Frankfurt 2002, 201.
  14. Charles S. Peirce: The Thought and Logic of the Universe. The Cambridge Conferences Lectures of 1898 , ed. By Kenneth Laine Ketner, Suhrkamp, ​​Frankfurt 2002, 202.
  15. ^ Wilhelm Dilthey: The structure of the historical world in the humanities [Berlin 1910], Collected Writings Volume VII, ed. by Bernhard Groethuysen , Vandenhoeck & Ruprecht, 8th edition Göttingen 1992, 201.
  16. The theory of categories can be found in particular in Wilhelm Dilthey: The Structure of the Historical World in the Humanities [Berlin 1910], Collected Writings Volume VII, ed. by Bernhard Groethuysen , Vandenhoeck & Ruprecht, 8th edition, Göttingen 1992: Die Categories des Lebens, 228–245, as well as in Gesammelte Schriften Volume XIX an elaboration with the title: Life and Recognition, a draft for epistemological logic and theory of categories, approx. 1892/93, 338-388.
  17. Collected Writings Volume XIX: Living and Recognizing, 338–388, 361.
  18. Collected Writings Volume XIX: Living and Recognizing, 338–388, 361.
  19. Otto Friedrich Bollnow: Dilthey and the phenomenology, in: Dilthey and the philosophy of the present. Edited and introduced by Ernst Wolfgang Orth. Alber Freiburg 1985, pp. 31–61 ( online ( memento of the original from October 31, 2007 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. ). @1@ 2Template: Webachiv / IABot /
  20. Collected Writings Volume XIX: Life and Recognition, 338–388, 362.
  21. Collected Writings Volume XIX: Life and Recognition, 338–388, 369.
  22. Collected Writings Volume XIX: Living and Recognizing, 338–388, 374.
  23. Collected Writings Volume XIX: Living and Recognizing, 338–388, 379.
  24. Gernot Böhme : Whitehead's departure from substance metaphysics. In: Ernest Wolf-Gazo (Ed.): Whitehead, Alber, Freiburg / Munich 1980, 45–53, 52.
  25. Process and Reality is quoted in the text with the code PR after the German edition: Alfred North Whitehead: Prozess und Reality. Draft of a cosmology. Translated and provided with an afterword by Hans Günter Holl, Suhrkamp, ​​2nd verb. Ed., 'Frankfurt 1987.
  26. quoted from: Michael Hauskeller: Whitehead for an introduction. Junius, Hamburg 1994, 80.
  27. Reto Luzius Fetz translates the term "categorical obligations" as "categorial conditions", in: Whitehead: Process Thinking and Substance Metaphysics, Alber, Freiburg / Munich 1981, 113.
  28. Holm Breuer, entry: Ontology in Wulff D. Rehfuss, hand dictionary of philosophy, UTB 2003, ISBN 3-8252-8208-2 .
  29. Reinhardt Grossmann: The existence of the world. An introduction to ontology, Ontos, Frankfurt 2004, 65.
  30. Baumgartner et al., Category, Categories Theory, 1976, pp. 714-776.
  31. Klaus Hartmann : Hegel's Logic , ed. by Olaf L. Müller , de Gruyter, Berlin 1999.
  32. Tasks and methods of a category theory. In: Kant studies 52, 1960/61, 351–368
  33. Category theory, Carl Dunker's, Berlin 1896; 2nd Edition. in three volumes, Meiner, Leipzig 1923, see: Jean-Claude Wolf: Eduard von Hartmann. Philosopher of the early days , Königshausen and Neumann, Würzburg 2006.
  34. Michael Elmentaler: Logical-semantic studies in the grammar of the early 19th century: Studies on the theory of categories by Simon Heinrich Adolf Herling , de Gruyter Berlin 1966.
  35. The concept of wholeness and the Kantian philosophy. Ideas for a regional logic and category theory. Reinhardt, Munich 1927.
  36. On the logic and category theory of mathematical objects. To the entirety of the theoretical subject, with particular reference to the mathematical problem of existence. Dores, Erlangen 1937 (dissertation) and presented more tightly as: On logic and the theory of categories of mathematical objects, in: Philosophy in Self-Representations Volume II, ed. By Ludwig Pongratz, Meiner, Hamburg 1977.
  37. The logic of philosophy and the theory of categories. A study of the domain of logical form , JCB Mohr (Paul Siebeck), Tübingen 1911.
  38. The logic of the critique of reason. Kant's theory of categories in their current meaning. An introduction. Francke 1986 or in a revised version: The secret of the categories. The decryption of Kant's central teaching piece. MAAS, Berlin 2004.
  39. Othmar Spann: Category theory. Supplementary volumes to the Herdflamme Collection , Vol. 1. Jena 1924.