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Predicables is, in scholastic logic
Term logic
In philosophy, term logic, also known as traditional logic or aristotelian logic, is a loose name for the way of doing logic that began with Aristotle and that was dominant until the advent of modern predicate logic in the late nineteenth century...

, a term applied to a classification
Categorization is the process in which ideas and objects are recognized, differentiated and understood. Categorization implies that objects are grouped into categories, usually for some specific purpose. Ideally, a category illuminates a relationship between the subjects and objects of knowledge...

 of the possible relations in which a predicate may stand to its subject
Subject (philosophy)
In philosophy, a subject is a being that has subjective experiences, subjective consciousness or a relationship with another entity . A subject is an observer and an object is a thing observed...

. It is not to be confused with 'praedicamenta', the schoolmen's
Scholasticism is a method of critical thought which dominated teaching by the academics of medieval universities in Europe from about 1100–1500, and a program of employing that method in articulating and defending orthodoxy in an increasingly pluralistic context...

 term for Aristotle
Aristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...

's ten Categories
Categories (Aristotle)
The Categories is a text from Aristotle's Organon that enumerates all the possible kinds of thing that can be the subject or the predicate of a proposition...


The list given by the schoolmen and generally adopted by modern logicians is based on the original fivefold classification given by Aristotle (Topics
Topics (Aristotle)
The Topics is the name given to one of Aristotle's six works on logic collectively known as the Organon. The other five are:*Categories*De Interpretatione*Prior Analytics*Posterior Analytics*On Sophistical Refutations...

, a iv. 101 b 17-25): definition
A definition is a passage that explains the meaning of a term , or a type of thing. The term to be defined is the definiendum. A term may have many different senses or meanings...

 (horos), genus
Genus (philosophy)
In Scholastic logic a Genus is one of the Predicables. Genus is that part of a definition which is also predicable of other things different from the definiendum. A triangle is a rectilineal figure; i.e. in fixing the genus of a thing, we subsume it under a higher universal, of which it is a...

 (genos), differentia
In Scholastic logic, differentia is one of the predicables. It is that part of a definition which is predicable in a given genus only of the definiendum....

 (diaphora), property (idion), accident
Accident (philosophy)
Accident, as used in philosophy, is an attribute which may or may not belong to a subject, without affecting its essence. The word "accident" has been employed throughout the history of philosophy with several distinct meanings....

 (sumbebekos). The scholastic classification, obtained from Boëthius
Anicius Manlius Severinus Boethius
Anicius Manlius Severinus Boëthius, commonly called Boethius was a philosopher of the early 6th century. He was born in Rome to an ancient and important family which included emperors Petronius Maximus and Olybrius and many consuls. His father, Flavius Manlius Boethius, was consul in 487 after...

's Latin version of Porphyry
Porphyry (philosopher)
Porphyry of Tyre , Porphyrios, AD 234–c. 305) was a Neoplatonic philosopher who was born in Tyre. He edited and published the Enneads, the only collection of the work of his teacher Plotinus. He also wrote many works himself on a wide variety of topics...

's Isagoge
The Isagoge or "Introduction" to Aristotle's "Categories", written by Porphyry in Greek and translated into Latin by Boethius, was the standard textbook on logic for at least a millennium after his death. It was composed by Porphyry in Sicily during the years 268-270, and sent to Chrysaorium,...

, modified Aristotle's by substituting species (eidos) for definition. Both classifications are of universals
Universal (metaphysics)
In metaphysics, a universal is what particular things have in common, namely characteristics or qualities. In other words, universals are repeatable or recurrent entities that can be instantiated or exemplified by many particular things. For example, suppose there are two chairs in a room, each of...

, concepts or general terms
Terminology is the study of terms and their use. Terms are words and compound words that in specific contexts are given specific meanings, meanings that may deviate from the meaning the same words have in other contexts and in everyday language. The discipline Terminology studies among other...

, proper names of course being excluded. There is, however, a radical difference between the two systems. The standpoint of the Aristotelian classification is the predication of one universal concerning another. The Porphyrian, by introducing species, deals with the predication of universals concerning individuals (for species is necessarily predicated of the individual), and thus created difficulties from which the Aristotelian is free (see below).

The Aristotelian classification may be briefly explained:
  • The definition of anything is the statement of its essence
    In philosophy, essence is the attribute or set of attributes that make an object or substance what it fundamentally is, and which it has by necessity, and without which it loses its identity. Essence is contrasted with accident: a property that the object or substance has contingently, without...

    (Arist. to ti en einai), i.e. that which makes it what it is: e.g. a triangle is a three-sided rectilineal figure.
  • Genus is that part of the essence which is also predicable of other things different from them in kind. A triangle is a rectilineal figure; i.e. in fixing the genus of a thing, we subsume it under a higher universal, of which it is a species.
  • Differentia is that part of the essence which distinguishes one species from another. As compared with quadrilaterals, hexagons and so on, all of which are rectilineal figures, a triangle is differentiated as having three sides.
  • A property is an attribute which is common to all the members of a class, but is not part of its essence (i.e. need not be given in its definition). The fact that the interior angles of all triangles are equal to two right angles is not part of the definition, but is universally true.
  • An accident is an attribute which may or may not belong to a subject. The color of the human hair is an accident, for it belongs in no way to the essence of humanity.

This classification, though it is of high value in the clearing up of our conceptions of the essential contrasted with the accidental, the relation of genus, differentia and definition and so forth, is of more significance in connection with abstract sciences, especially mathematics, than for the physical sciences. It is superior on the whole to the Porphyrian scheme, which has grave defects. As has been said, it classifies universals as predicates of individuals and thus involves the difficulties which gave rise to the controversy between realism and nominalism. How are we to distinguish species from genus? Napoleon was a Frenchman, a man, an animal. In the second place how do we distinguish property and accident? Many so-called accidents are predicable necessarily of any particular persons. This difficulty gave rise to the distinction of separable and inseparable accidents, which is one of considerable difficulty.