A trichotomy is a three-way classificatory division. Some philosophers pursued trichotomies.

Important trichotomies discussed by Aquinas include the causal principles (agent, patient, act), the potencies for the intellect (imagination, cogitative power, and memory and reminiscence), and the acts of the intellect (concept, judgment, reasoning),
with all of those rooted in Aristotle; also the transcendentals of being (unity, truth, goodness) the requisites of the beautiful (wholeness, harmony, radiance).

Kant

Immanuel Kant

Immanuel Kant was a German philosopher from Königsberg , researching, lecturing and writing on philosophy and anthropology at the end of the 18th Century Enlightenment....

 expounded a table of judgments involving four three-way alternatives, in regard to (1) Quantity, (2) Quality, (3) Relation, (4) Modality, and, based thereupon, a table of four categories, named by the terms just listed, and each with three subcategories. Kant also adapted the Thomistic acts of intellect in his trichotomy of higher cognition — (a) understanding, (b) judgment, (c) reason — which he correlated with his adaptation in the soul's capacities — (a) cognitive faculties, (b) feeling of pleasure or displeasure, and (c) faculty of desire — of Tetens

Johannes Nikolaus Tetens

Johannes Nikolaus Tetens was a German philosopher, statistician and scientist.He has been called 'the German Hume', on the basis of a comparison of his major work Philosophische Versuche über die menschliche Natur und ihre Entwickelung with David Hume's A Treatise of Human Nature...

's trichotomy of feeling, understanding, will.

Hegel

Georg Wilhelm Friedrich Hegel

Georg Wilhelm Friedrich Hegel was a German philosopher, one of the creators of German Idealism. His historicist and idealist account of reality as a whole revolutionized European philosophy and was an important precursor to Continental philosophy and Marxism.Hegel developed a comprehensive...

 held that a thing's or idea's internal contradiction leads in a dialectical process to a new synthesis that makes better sense of the contradiction. The process is sometimes described as thesis, antithesis, synthesis. It is instanced across a pattern of trichotomies (e.g. being-nothingness-becoming, immediate-mediate-concrete, abstract-negative-concrete); such trichotomies are not just three-way classificatory divisions; they involve trios of elements functionally interrelated in a process. They are often called triads (but 'triad' does not have that as a fixed sense in philosophy generally).

Charles Sanders Peirce built his philosophy on trichotomies and triadic relations and processes, and framed the "Reduction Thesis

Categories (Peirce)

On May 14, 1867, the 27-year-old Charles Sanders Peirce, who eventually founded Pragmatism, presented a paper entitled "On a New List of Categories" to the American Academy of Arts and Sciences. Among other things, this paper outlined a theory of predication involving three universal categories...

" that every predicate is essentially either monadic (quality), dyadic (relation of reaction or resistance), or triadic (representational relation), and never genuinely and irreducibly tetradic or larger.

In theology

Theology

Theology is the systematic and rational study of religion and its influences and of the nature of religious truths, or the learned profession acquired by completing specialized training in religious studies, usually at a university or school of divinity or seminary.-Definition:Augustine of Hippo...

, and in philosophy

Philosophy

Philosophy is the study of general and fundamental problems, such as those connected with existence, knowledge, values, reason, mind, and language. Philosophy is distinguished from other ways of addressing such problems by its critical, generally systematic approach and its reliance on rational...

 related to it, trichotomy is the belief that man consists of three parts; a body

Body

With regard to living things, a body is the physical body of an individual. "Body" often is used in connection with appearance, health issues and death...

, soul

Soul

A soul in certain spiritual, philosophical, and psychological traditions is the incorporeal essence of a person or living thing or object. Many philosophical and spiritual systems teach that humans have souls, and others teach that all living things and even inanimate objects have souls. The...

, and spirit

Spirit

The English word spirit has many differing meanings and connotations, most of them relating to a non-corporeal substance contrasted with the material body.The spirit of a living thing usually refers to or explains its consciousness.The notions of a person's "spirit" and "soul" often also overlap,...

. This stands in stark contrast to dichotomy

Dichotomy

A dichotomy is any splitting of a whole into exactly two non-overlapping parts, meaning it is a procedure in which a whole is divided into two parts...

.

Examples

3-way Philosophical Distinctions

Plato Plato Plato , was a Classical Greek philosopher, mathematician, student of Socrates, writer of philosophical dialogues, and founder of the Academy in Athens, the first institution of higher learning in the Western world. Along with his mentor, Socrates, and his student, Aristotle, Plato helped to lay the... 's Tripartite soul	Rational. Libidinous. Spirited (various animal qualities).
St. Augustine's Augustine of Hippo Augustine of Hippo , also known as Augustine, St. Augustine, St. Austin, St. Augoustinos, Blessed Augustine, or St. Augustine the Blessed, was Bishop of Hippo Regius . He was a Latin-speaking philosopher and theologian who lived in the Roman Africa Province...  3 Laws	Divine Law. Natural Law. Temporal, positive, or human Law.
St. Augustine's Augustine of Hippo Augustine of Hippo , also known as Augustine, St. Augustine, St. Austin, St. Augoustinos, Blessed Augustine, or St. Augustine the Blessed, was Bishop of Hippo Regius . He was a Latin-speaking philosopher and theologian who lived in the Roman Africa Province...  3 characterizations of the soul	Memory. Understanding. Will.
Aquinas's Thomas Aquinas Thomas Aquinas, O.P. , also Thomas of Aquin or Aquino, was an Italian Dominican priest of the Catholic Church, and an immensely influential philosopher and theologian in the tradition of scholasticism, known as Doctor Angelicus, Doctor Communis, or Doctor Universalis...  3 causal principles (based in Aristotle)	Agent. Patient. Act.
Aquinas's 3 potencies for intellect (based in Aristotle)	Imagination. Cogitative power (or, in animals, instinct). Memory (and, in humans, reminiscence).
Aquinas's 3 acts of intellect (based in Aristotle)	Conception. Judgment. Reasoning.
Aquinas's 3 transcendentals of being	Unity. Truth. Goodness.
Aquinas's 3 requisites for the beautiful	Wholeness or perfection. Harmony or due proportion. Radiance.
Albertus Magnus Albertus Magnus Albertus Magnus, O.P. , also known as Albert the Great and Albert of Cologne, is a Catholic saint. He was a German Dominican friar and a bishop, who achieved fame for his comprehensive knowledge of and advocacy for the peaceful coexistence of science and religion. Those such as James A. Weisheipl... 's 3 Universals	Ante rem (Idea in God's mind). In re (potential or actual in things). Post rem (mentally abstracted).
Sir Francis Bacon Francis Bacon Francis Bacon, 1st Viscount St Albans, KC was an English philosopher, statesman, scientist, lawyer, jurist, author and pioneer of the scientific method. He served both as Attorney General and Lord Chancellor of England... 's 3 Tables	Presence. Absence. Degree.
Thomas Hobbes Thomas Hobbes Thomas Hobbes of Malmesbury , in some older texts Thomas Hobbs of Malmsbury, was an English philosopher, best known today for his work on political philosophy... 's 3 Fields	Physics. Moral Philosophy. Civil Philosophy.
Johannes Nikolaus Tetens Johannes Nikolaus Tetens Johannes Nikolaus Tetens was a German philosopher, statistician and scientist.He has been called 'the German Hume', on the basis of a comparison of his major work Philosophische Versuche über die menschliche Natur und ihre Entwickelung with David Hume's A Treatise of Human Nature... 's 3 powers of mind	Feeling. Understanding. Will.
John Dryden John Dryden John Dryden was an influential English poet, literary critic, translator, and playwright who dominated the literary life of Restoration England to such a point that the period came to be known in literary circles as the Age of Dryden.Walter Scott called him "Glorious John." He was made Poet... 's 3 ways of transferring	Metaphrase Metaphrase Metaphrase is a translation term referring to literal translation, i.e., "word by word and line by line" translation. In everyday usage, metaphrase means literalism; however, metaphrase is also the translation of poetry into prose... . Paraphrase Paraphrase Paraphrase is restatement of a text or passages, using other words. The term "paraphrase" derives via the Latin "paraphrasis" from the Greek , meaning "additional manner of expression". The act of paraphrasing is also called "paraphrasis."... . Imitation.
Kant Immanuel Kant Immanuel Kant was a German philosopher from Königsberg , researching, lecturing and writing on philosophy and anthropology at the end of the 18th Century Enlightenment.... 's 3 faculties of soul	Faculties of knowledge. Feeling of pleasure or displeasure. Faculty of desire (which Kant regarded also as the will).
Kant's 3 higher faculties of cognition	Understanding. Judgment. Reason.
Kant's 3 judgments of quantity	Universal. Particular Particular In philosophy, particulars are concrete entities existing in space and time as opposed to abstractions. There are, however, theories of abstract particulars or tropes. For example, Socrates is a particular... . Singular
Kant's 3 categories of quantity	Unity. Plurality. Totality Absolute (philosophy) The Absolute is the concept of an unconditional reality which transcends limited, conditional, everyday existence. It is sometimes used as an alternate term for "God" or "the Divine", especially, but by no means exclusively, by those who feel that the term "God" lends itself too easily to...
Kant's 3 judgments of quality	Affirmative Positive (linguistics) Positive is the form of an adjective or adverb on which comparative and superlative are formed, in English, with the suffixes -ier, -lier, -iest, or -liest, or the forms more/less for polysyllabic adjectives/adverbs. In English, good is a positive adjectival form corresponding to the comparative... . Negative. Infinite Infinity Infinity is a concept in many fields, most predominantly mathematics and physics, that refers to a quantity without bound or end. People have developed various ideas throughout history about the nature of infinity...
Kant's 3 categories of quality	Reality Reality In philosophy, reality is the state of things as they actually exist, rather than as they may appear or might be imagined. In a wider definition, reality includes everything that is and has been, whether or not it is observable or comprehensible... . Negation Negation In logic and mathematics, negation, also called logical complement, is an operation on propositions, truth values, or semantic values more generally. Intuitively, the negation of a proposition is true when that proposition is false, and vice versa. In classical logic negation is normally identified... . Limitation.
Kant's 3 judgments of relation	Categorical Categorical imperative The Categorical Imperative is the central philosophical concept in the moral philosophy of Immanuel Kant, as well as modern deontological ethics... . Hypothetical. Disjunctive Logical disjunction In logic and mathematics, a two-place logical connective or, is a logical disjunction, also known as inclusive disjunction or alternation, that results in true whenever one or more of its operands are true. E.g. in this context, "A or B" is true if A is true, or if B is true, or if both A and B are... .
Kant's 3 categories of relation	Inherence Inherence Inherence refers to Empedocles' idea that the qualities of matter come from the relative proportions of each of the four elements entering into a thing. The idea was further developed by Plato and Aristotle....  and subsistence. Causality Causality Causality is the relationship between an event and a second event , where the second event is understood as a consequence of the first....  and dependence. Community.   In other words: Substance Substance theory Substance theory, or substance attribute theory, is an ontological theory about objecthood, positing that a substance is distinct from its properties. A thing-in-itself is a property-bearer that must be distinguished from the properties it bears....  and accident Accident An accident or mishap is an unforeseen and unplanned event or circumstance, often with lack of intention or necessity. It implies a generally negative outcome which may have been avoided or prevented had circumstances leading up to the accident been recognized, and acted upon, prior to its... . Cause Causality Causality is the relationship between an event and a second event , where the second event is understood as a consequence of the first....  and effect Result A result is the final consequence of a sequence of actions or events expressed qualitatively or quantitatively. Possible results include advantage, disadvantage, gain, injury, loss, value and victory. There may be a range of possible outcomes associated with an event depending on the point of... . Reciprocity.
Kant's 3 judgments of modality	Problematical. Assertoric Assertoric An assertoric proposition in Aristotelian logic merely asserts that something is the case, in contrast to problematic propositions which assert the possibility of something being true, or apodeictic propositions which assert things which are necessarily or self-evidently true or false. For... . Apodictic
Kant's 3 categories of modality	Possibility Subjunctive possibility Subjunctive possibility is the form of modality most frequently studied in modal logic... . Existence Existence In common usage, existence is the world we are aware of through our senses, and that persists independently without them. In academic philosophy the word has a more specialized meaning, being contrasted with essence, which specifies different forms of existence as well as different identity... . Necessity Necessity In U.S. criminal law, necessity may be either a possible justification or an exculpation for breaking the law. Defendants seeking to rely on this defense argue that they should not be held liable for their actions as a crime because their conduct was necessary to prevent some greater harm and when...
Hegel's Georg Wilhelm Friedrich Hegel Georg Wilhelm Friedrich Hegel was a German philosopher, one of the creators of German Idealism. His historicist and idealist account of reality as a whole revolutionized European philosophy and was an important precursor to Continental philosophy and Marxism.Hegel developed a comprehensive...  3 dialectical moments	Thesis. Antithesis. Synthesis.
Hegel's 3 Spirits	Subjective Spirit. Objective Spirit. Absolute Spirit.
Charles Sanders Peirce's 3 categories Categories (Peirce) On May 14, 1867, the 27-year-old Charles Sanders Peirce, who eventually founded Pragmatism, presented a paper entitled "On a New List of Categories" to the American Academy of Arts and Sciences. Among other things, this paper outlined a theory of predication involving three universal categories...	Quality of feeling. Reaction, resistance. Representation, mediation.
C. S. Peirce's 3 universes of experience	Ideas. Brute fact. Habit (habit-taking).
C. S. Peirce's 3 orders of philosophy	Phenomenology. Normative sciences. Metaphysics.
C. S. Peirce's 3 normatives	The good (esthetic). The right (ethical). The true (logical).
C. S. Peirce's 3 semiotic elements Semiotic elements and classes of signs (Peirce) Logician, mathematician, philosopher, and scientist Charles Sanders Peirce began writing on semeiotic, semiotics, or the theory of sign relations in the 1860s, around the time that he devised his system of three categories...	Sign (representamen). Object. Interpretant.
C. S. Peirce's 3 grades of conceptual clearness Pragmaticism Pragmaticism is a term used by Charles Sanders Peirce for his pragmatic philosophy starting in 1905, in order to distance himself and it from pragmatism, the original name, which had been used in a manner he did not approve of in the "literary journals"...	By familiarity. Of definition's parts. Of conceivable practical implications.
C. S. Peirce's 3 active principles in the cosmos	Spontaneity, absolute chance. Mechanical necessity. Creative love.
Gottlob Frege Gottlob Frege Friedrich Ludwig Gottlob Frege was a German mathematician, logician and philosopher. He is considered to be one of the founders of modern logic, and made major contributions to the foundations of mathematics. He is generally considered to be the father of analytic philosophy, for his writings on... 's 3 realms of sense	The external, public, physical. The internal, private, mental. The Platonic, ideal but objective (to which sentences refer).
Karl Popper's 3 worlds	Physical things and processes. Subjective human experience. Culture and objective knowledge
James Joyce James Joyce James Augustine Aloysius Joyce was an Irish novelist and poet, considered to be one of the most influential writers in the modernist avant-garde of the early 20th century... 's 3 aesthetic stages	Arrest (by wholeness). Fascination (by harmony). Enchantment (by radiance).
Louis Zukofsky Louis Zukofsky Louis Zukofsky was an American poet. He was one of the founders and the primary theorist of the Objectivist group of poets and thus an important influence on subsequent generations of poets in America and abroad.-Life:... 's 3 aesthetic elements	Shape. Rhythm. Style.
Søren Kierkegaard Søren Kierkegaard Søren Aabye Kierkegaard was a Danish Christian philosopher, theologian and religious author. He was a critic of idealist intellectuals and philosophers of his time, such as Georg Wilhelm Friedrich Hegel, Friedrich Wilhelm Joseph Schelling and Karl Wilhelm Friedrich Schlegel... 's 3 Stages	Aesthetic. Ethical. Religious.
Edmund Husserl Edmund Husserl Edmund Gustav Albrecht Husserl was a philosopher and mathematician and the founder of the 20th century philosophical school of phenomenology. He broke with the positivist orientation of the science and philosophy of his day, yet he elaborated critiques of historicism and of psychologism in logic... 's 3 Reductions	Phenomenological. Eidetic. Religious.
Maurice Merleau-Ponty Maurice Merleau-Ponty Maurice Merleau-Ponty was a French phenomenological philosopher, strongly influenced by Karl Marx, Edmund Husserl and Martin Heidegger in addition to being closely associated with Jean-Paul Sartre and Simone de Beauvoir... 's 3 fields	Physical. Vital. Human.
Maurice Merleau-Ponty's 3 categories	Quantity. Order. Meaning.
Alan Watts Alan Watts Alan Wilson Watts was a British philosopher, writer, and speaker, best known as an interpreter and popularizer of Eastern philosophy for a Western audience. Born in Chislehurst, he moved to the United States in 1938 and began Zen training in New York... 's 3 world views	Life as machine (Western). Life as organism (Chinese). Life as drama (Indian).