Individuation principle

The means by which separate items or individuals are distinguished.

Debate over the years has centred upon the question of whether such individuation is achieved through some inherent characteristic or through some formal acceptance of a necessary ‘uniqueness’ belonging to every being and object.

Single items


The question of the principle of individuation played a major role in Aristotelian metaphysics and in the systems of medieval scholasticism based on it . Aristotle had rejected the separation of the general and the individual in Plato’s philosophy and had taken the general back into things. However, since he could not gain a correct understanding of how the relationship between the general and the individual should be thought of in things, he developed his material (matter) form schematism, which ultimately could not overcome the basic error of Platonic theory. He understood individuation as a synolon , as a composition of form and material ( hylemorphism ). Avicenna specified this connection in his metaphysics: “Cum enim materia sola principium sit individuationis et nihil sit singulare nisi materia vel per materiam … dicimus omnes formas potentia esse in materia et per motum educi de ipsa”. The Platonic idea thus became the concept of form , and what remained was the particularity of the general as well as its general elevation and valuation. Under these circumstances the following problem had to occur:

For the composition of form and matter

If the general type of species is derived from form, what is the reason for the diversity of objects within the species? To this question Aristotle answered: it is the substance (matter) that determines the individuation. Every being is a composition of form and matter , the former being responsible for the general, the latter for the individual (in: Metaphysik, VII, 8). Since this conception caused considerable ambiguity in its time, because it was not clear how matter, as a pure potency and thus completely indeterminate, should bring about individuation. Since this view had considerable consequences for the value of the human person, a long and violent dispute arose in the period that followed, especially in the Middle Ages, over the principle of individuation.

middle Ages

Thomas Aquinas and his followers basically followed the teachings of Aristotle, who saw in the materia signata vel individualis the concrete material, the matter endowed with certain proportions and dimensions, as the principium individuationis. The materia sensibus signata is individuationis et singularitatis principium . And formae, quae sunt receptibiles, in materia individuantur per materiam, quae non potest esse in alio . Materia non quomodolibet accepta est principium individuationis, sed solum materia signata (in: De ente et essentia , 1250).

From the point of view of the older Franciscan school ( Alexander von Hales , Bonaventura ), neither an indefinite substratum, which is close to nothing, nor an accident like quantity can be the basis of individuation. The individuation is rather derived from the actual connection of matter and form (in Bonaventura matter is the hoc esse , the form aliquid esse ) and their mutual empowerment: Individuatio est ex communicatione materia cum forma . The numerical individuality is based on the material, the qualitative individuality on the form. He tried to support this view by assuming a majority of the forms for beings and also teaching of matter that it is completely indeterminate.

In Heinrich von Gent , Roger Bacon , Richard von Middletown and Duns Scotus , the principle of individuation can be seen in the form. Accordingly, a variety of forms (i.e., individual ideas) are adopted. The form of “whatness” ( quidditas ) becomes the form of “thisness” ( haecceitas ). And unitas individui consequitur aliquam entitatem aliam determinantem istam, et illa faciet unum per se cum entitate naturae .

For the nominalists ( Roscelin von Compiègne , Durandus von St. Pourçain , Wilhelm von Ockham and his school) the reason for individuation lies in the individual itself. There is only the individual and the individual. With this view, however, the question of the principle of individuation became practically irrelevant. This was also expressly emphasized by the various nominalists (Durand von St. Pourcain, Petrus Aureoli ). The problem of the principle of individuation is a wrongly asked question. The question is not: What must be added to the general in the object in order for it to become individual; the question is the other way around: there are principally individual things – and we must ask what the reason for the general is, what justifies us to speak of objects that have always been individual in the form of generality.


Although the question was already adequately posed in the doctrine of nominalism, the discussion about the principle of individuation and the problem of the individual (i.e. the individual) that was hidden behind it continued in the following period. In the philosophy of the Renaissance it was above all Nikolaus von Kues , Giordano Bruno , Agrippa von Nettesheim , Johann Baptist van Helmont , Franciscus Mercurius van Helmont , Paracelsus and Valentin Weigel who discussed the problem, whereby they increasingly emphasized the independence and value of the Emphasized the individual and pushed back the traditional overestimation of the general and its metaphysical separation from the individual.


The teachings of Gottfried Wilhelm Leibniz represented a high point and, at the same time, a certain conclusion to this discussion . In his work On the Individuation Principle (1663), he dealt with the previous views and showed that only the nominalists showed the right way, while all others Attempts to solve this problem have not stood up to criticism. According to Leibniz, the solution to the problem lies in the recognition that in reality only individuals exist and that one does not seek the ground of individuation in any part of things, but rather that objects are individualized on the basis of their overall entity. His principle was therefore: Each individual is individuated by his whole entity .


According to Arthur Schopenhauer’s The World as Will and Idea (1819), the basic principle of all being is the will (to exist), which as such cannot be further questioned. If this will is the “ thing in itself ” following Kant , then every concrete being, the ontology of everything that exists in spatiotemporal form, is the effect of the “principium individuationis” that this primordial will develops from itself: the world the apparition, the “veil of the Maya” . The individuation principle, as the opposition of the one will to the many individual wills, is the cause of suffering and requires philosophical penetration ( Tat Tvam Asi ), which leads to an ethically motivated, as it were Buddhist denial of the will.

Analytical philosophy

In analytical philosophy there are strongly diverging positions with regard to the individuation problem. For ontologists from the empirical tradition, what is individuating in a concrete individual thing is the “bundle of properties” that belongs to it. According to this bundle theory , all of an individual’s properties are essential. The properties represent the only “components” of the individuals; it is a “one-category ontology”. Another point of view relocates the principle of individuation to the spatiotemporal determinations of a single thing. Furthermore, there are positions that assume that individual things have certain essential properties that belong to a thing at all times of its existence. The “individual form” or the “concrete realized form” ( form token ) of a single thing are mentioned. Another group of viewpoints assumes that the individuation principle cannot be reduced to anything more fundamental. According to this, the individuality of a thing is not given by any of its properties, but by the so-called bare particular , the pure substratum, which is the bearer of all properties. Another view from the field of analytical philosophy corresponds to that of medieval haecceitas . According to this, every single thing is individuated by the determination to be exactly this there.

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