ACCIDENT (Greek, συμβεβηκος Latin accidens — a property, nonessential feature, accident). In ordinary speech this is an accident, a property, something insignificant and not essential; in philosophy it is a non-necessary and non-essential element, something that belongs to something else, something that inheres in something else.
The term "accident" is applied in philosophy to describe a mode of existence of being (an accidental mode) or of an element in being, and also of a property of being. In the logic of natural language, an accident means a category of predicates that predicate accidental features of a subject in a sentence.
A GENERAL UNDERSTANDING OF ACCIDENT. Following Aristotle, an accident may be interpreted in two ways in philosophy, either in metaphysical terms or in logical terms. In Thomas Aquinas' metaphysical interpretation, "an accident is something which is real, and which cannot exist on its own, but only in a substrate which is called a subject or substance" (In IV Sent.,m d. 1, a. 1, soll.). An accident as such as something which comes from an external source to a subject or substance, but which is virtually inherent in the subject's potency and thereby the subject or substance is revealed and perfected. Accidents as real properties of beings are the basis for distinguishing the categories of predicates whereby the logic of language and the logic of predication have a rational justification in the structure of being.
Aristotle discovered the subontological compositions of matter and form and these were the basis for his doctrine that things are not aggregates of independently existing parts, and that the whole is something greater than the sum of a thing's parts. Not all the elements or parts that occur in things exist independently in the manner of a whole thing. There are certain elements which sustain other elements, and there are elements that are sustained. The former elements are autonomous in their existence since they exist in themselves and have the power of imparting being to the elements that are sustained and cannot exist on their own. In this way we may distinguish in each thing the substantial element that has being in itself (it exists in itself — ens in se), and accidental elements that have being because of something else (they exist in another thing — ens in alio). Before Aristotle, philosophers did not distinguish between substantial and accidental elements, or necessary and non-necessary elements. They thought that everything that composes a being has the same nature.
The fact that Aristotle distinguished accidents as non-independent factors that modify a subject or substance allowed him to resolve the aporiai of his predecessors concerning the question whether true being is absolutely unchanging and identical with itself or capable of change and composite.
Accidents determine the wealth of content in the concrete being. Because of them, particular beings have a wealth of content and create among themselves definite relations and are subject to definite determinations (such as magnitude, color, and shape). They occupy a place and exist at a definite time, undergo something or influence other things, etc.. Although accidents do not exist independently in the same way as a whole thing, they are not abstract or non-real. We will never encounter anywhere a color, shape, time, place or activity that exists on its own, but we encounter trees of a certain color, things with definite shapes, people who live at a particular time and in a particular place, etc.. Accidents receive their being and reality from the subject or substance in which they are located; the presence or absence of an accident affects the modification of the entire being. This modification can include the being as a whole or merely some aspect of the being.
CLASSIFICATION OF THE BASIC KINDS OF ACCIDENTS. Aristotle does not explain how he arrived at his classification of the basic categories of being. The first category is that of existence in the mode of a substance, namely something that exists in itself (ens in se). The other categories are existence in the mode of accidents, namely existence in something else (in alio). Accidents directly or indirectly modify a subject or substance. The first commentators on Aristotle accepted his division without question. Not until the 5th century did the Greek commentator, David the Armenian, try to present a rational justification for the division. He selected the division of independent and non-independent existence as his criterium of division.
Aristotle distinguished ten modes of existence and just as many modes of predication about being. However, when we consider the criterium of independence and non-independence, then both in the case of being and in the case of predication we have one essential mode of being and predication, and nine accidental modes. The categories of being were based on experience and underlie the theory of necessary and accidental predication. They are also the basis for apodeictic inference, which is also called syllogistics. In this way language, knowledge and demonstration are connected with the world of real things and are ordered to things.
Aristotle does not mention the entire canon of predicates in every passage. For example, in the Categories (1 b 25–2 a 4) he mentions ten of them. In the Posterior Analytics (83 a 21–23) he mentions eight. In Book IV of his Metaphysics (1089 b 23–1090 a 4) he mentions three. In each case, the predicates he mentions are dictated by the things he is considering in the particular books, and his various lists are not the result of inconsistency.
ACCIDENTS IN THEIR FUNCTION AS DIRECT OR INDIRECT MODIFICATIONS OF BEING. Aristotle counts quantity and quality among the accidents that modify a subject or substance entirely and directly. He presents various kinds of relations that occur in the framework of quantity and quality as accidents that modify their subjects indirectly. The extent of quantitative and qualitative modifications is very broad.
1. Quantity (Greek τ&omicron ποσον [to posón]; Latin, quantum). Aristotle writes "We call a quantity that which is divided into constituent parts, each or every one of which is by nature something one and individual. Thus plurality, if it is numerically calculable, is a kind of quantity." (Met. 1020 a 7–10). When we ask "how much of something is there", we discover the accident of the quantitative modification of being. Plurality and divisibility are natural modes of being in the world of real things. Because of its numerability, matter can be known with great precision, since the numerability of quantitative relations is connected with the structure of quantified matter. Number (one) is the measure of the numerability of quantitative relations. When a number is abstracted from its substrate, it is what is called a mathematical being and it serves the knowledge of matter's quantitative structure and all that is directly ordered to matter (e.g., magnitude, motion, time etc.).
2. Quality (Greek το ποιον [to poión]; Latin qualitas). Quality is anything apart from quantity that belongs to a substance (ibid., 1020 b 7). According to Aristotle, in its first and primary sense quality is that which distinguishes a thing in its essence. A second kind of quality are the properties of changing things insofar as they change, namely the properties in view of which changes are distinguished (ibid., 1020 b 14). When we ask, "how is something?", we discover the accident of the qualities of beings. In his Categories (8 b–10 a), Aristotle orders qualities into four groups: a) permanent and impermanent modes of being in substance (habitus — dispositio); b) faculties and inclinations ordered to action (potentia — impotentia); c) permanent and impermanent passions and transformations (passio — passibilis qualitas); d) shapes and geometric solids, namely the shaping of a thing in one or more dimensions (forma — figura).
3. Relation (Greek προς τι [pros ti]; Latin relatio). According to Aristotle, things that are relative, namely which refer to something, are that which "being either said to be of something else or related to something else, are explained by reference to that other thing." (Cat., 6 a 30). We discover relations when we ask "with whom (or what) is something?".
Relations (or references) can occur among concrete beings that exist independently (John and Eve as spouses), between elements within being (John as John) and between a substance and all its accidents. Relations can occur among constitutive elements (e.g., essence-existence, matter-form) or integrating elements (e.g., the feet, the head, the heart, etc.), and also among perfective elements (veracity, benevolence, smoothness, roundness etc.).
As a result of the various ways that particular things and their internal elements can be ordered to each other, these things are subject to definite modifications as they take on a relation character of being, i.e., something exists, for example, as "greater than something", as "ordered to something or someone" (e.g., the son in relation to his father and mother) etc.. We can call relative that which is composed in itself as a whole (e.g., John as a compositum of body and soul, a table as a composition of various elements ordered to a definite project or form, etc.); other relational things are "seeing" (the ordering of vision to an object), "hearing" (the ordering of the faculty of hearing to a sound), and "knowing", as well as "building" or "producing" etc. (Met., 1021 b 4–12).
The relations that occur between mental beings in the domain of knowledge are the basis for modifications of our cognition. Logic studies these relations. The discovery and definition of relation as such, namely actual ordering, are tasks of the reason, and so they are an expression of the act of knowledge. Thus cognition as such is subject to an appropriate modification that consists in an agreement with a known thing or things. The result of cognition is the acquisition of a knowledge and an understanding of a thing. "Being-cognition", namely our knowledge, is constituted by relations (or orderings) that the intellect reads in things and among things, as well as among judgments. The apprehension of the reference system among them is the basis for our understanding of reality and an expression of our thought.
4. Location (Greek το πο&upsilon.; [to pou] or τοπος [topos]; Latin ubi or locus). Aristotle regarded the modification of location as so obvious that it needed no explanation (Cat, 11 b). When we ask "where is something?" we discover a new accident of being. He describes place as "the boundary of a surrounding body which is in contact with a surrounded body" (Phys., 212 a). The accident of location makes it possible for us to know material beings more profoundly. There are objects whose natural place is to be in the air or water, in the mountains or valleys, in thought or on a sheet of paper. Furthermore, a particular person (e.g., John) lives or exists in Kraków, in America, or in the mountains, and particular elements exists in the table or in the lumber etc..
5. Conditioning by time (Greek το ποτ&epsilon [to poté] or ωρα [hora], Latin quando or tempus). When we ask "when is something?", we discover a new accident and a new modification of being. The modification of material things with respect to time is directly connected with motion, which is a mode of existence for the whole world and particular material substances. It is in view of time that things are "two years old", "five years old", "today" or "yesterday", "modern" or "ancient" etc.. Time is conceived as the quantitative aspect of motion, yet in this case quantity, in accordance with Aristotle's explanations, can be understood in two ways: "it will be both that which is counted or is countable, and that by which we count. Time is that which is counted, and not a means for counting" (ibid., 219 b). Time is thus that which modifies a being according to "now"; "now" defines the time of a thing's existence as "before" and "after".
The modifications caused by time show the transitory character of things, their definite duration, occurrence etc. — there is the time of a man's life, the time of social and political changes (someone was a political activist for five years, another prepared two weeks for exams, and someone else has been building his house for two years). As we see, the existence of material beings undergoes a definite modification with respect to time. Some people associate time only with man's conscious subjective experience, but time is the objective measure of motion which is a mode of being in real things.
6. Action (Greek το ποιειν [to poiéin]; Latin actio). Various kinds of action that the subject elicits from himself modify his mode of being. The kind of modification which is action contains various opposites within it. Actions include heating and cooling, rejoicing and becoming sad, building and demolishing ("building" is a modification concern John's mode of existence as "builder", "writing" is a modification of John's existence as "writer" etc.).
Action as such allows us to know and understand the subject or substance better. It reveals the subject as a source of action and reveals the subject thereby as an efficient cause. The nature of a being is manifested by action, hence the question of whether and how a being acts is a question that manifests a new accident of being and reveals its nature.
7. Passion (Greek το πασχειν [to páschein]; Latin passio). When we ask how someone feels an action, we discover a new accident and a new modification of being — passion. Aristotle defines passion as follows: "Passion in one sense is the same quality in virtue of which a thing can undergo change. For example, to be white or black, sweet or bitter, heavy or light and the like. In another sense, passion is the actualization of these properties, namely changes that have occurred in these qualities. Passion also means changes of a certain kind, namely harmful changes, and especially those which cause pain. Great misfortunes and sufferings are called passions" (Met., 1022 b 15–22).
Passion like action encompasses opposites — one may experience joy and sorrow, suffering and pleasure, etc.. Passion is the counterpart of action. Passion is the experience of action, and action often causes internal transformation. Different kinds of action cause different kinds of passion, since the operations of action and passion are correlates.
Different kinds of modifications in being result from passion. The being that is passively undergoing something is changed and perfected. Modifications with respect to passion primarily concern the qualitative aspect of a substance. The subject or substance is the subject of passion. A substance in action is manifested as the efficient cause of definite effects, and in passion it is manifested as the cause of internal transformation in being.
8. Possession (Greek το εχειν [to échein]; Latin habere). We discover a new modification in being concerning possession when we ask "whose is this?". This modification shows the strict ordination of certain properties to definite beings. At the same time it shows substance as a subject capable of receiving these properties (for this reason, someone may have knowledge, but also may possess wealth; he may have particular skills, and also have respect among people etc.).
Aristotle explains: "'To have' is understood in various senses. It may mean to direct something in accordance with one's own nature or inclination. Whence we say that a fever 'possesses' a man, that tyrants 'possess' cities, and that people who wear clothes 'possess' them. In another sense, 'to have' means that something contains something else and is the substrate for it: bronze 'has' the shape of the statue, and the body 'has' the disease. 'To have' may also mean to contain something. For example, we say that a vessel has such and such a capacity, namely that it fits so much liquid, and that a city has men, and a ship has so many sailors. In this way we understand that the whole has parts. 'To have' is also used to describe a situation in which something prevents something else from moving or acting in accordance with its own inclination […] 'To have' is also understood as meaning something that holds things together that would otherwise disperse as each part acted in accordance with its own impulse." (Met, 1023 a 7–24).
Modifications with respect to possession frequently affect the position a man occupies in a social or cultural group (whether he is wealthy, educated, wise, circumspect etc.). This kind of modification also affects the wealth of his inner endowment.
9. Arrangement (Greek το κεισθαι [to kéisthai]; Latin situs). When we ask "how is something" we discover a new accident of being — arrangement. We see that properly arranged elements in a thing produce a whole (e.g., a brick house), and various things take the proper positions in relation to each other. This modification concerns the arrangement of various parts in relation to each other and to the whole.
The subject or substance expresses itself in various relations, both those of its own parts to the whole, and to things (e.g., we may arrange our body in various ways, and also take a certain posture before others). To remain in a certain position as a whole in relation to its parts, and also in relation to other things, is an important accident that modifies the subject or substance. Modifications with respect to arrangement or situation also concern a definite order of succession and the state of arrangement (to stand with a raised hand, to sit with legs folded etc.), and a person's inner feelings (to be satisfied, to feel well, etc.).
The above-mentioned accidents discovered by Aristotle, which directly or indirectly modify the existence of concrete things, are very essential for understanding the nature of really existing things. Because of his discovery of the accidents, Aristotle was able to avoid identifying the properties of a thing with the thing itself. He avoided identifying accidents with essence, or action with passion. He was able to avoid absolutizing and objectifying form, place, time, motion, space, relation etc., and thus avoided treating them as independent beings, which would have resulted in a distorted understanding of reality.
THE LOGICAL INTERPRETATION OF ACCIDENTS. The accidents listed above have been presented as factors that modify a subject or substance in a real way. Aristotle presented the accidents as the basis for various modes of predication about things. The particular kinds of modifications or accidents when apprehended in concepts and words may be treated as categories of predicates in a sentence. In a sentence, the subject or substance is that of which something is predicated, while the accident is the predicate, namely that which is predicated of something else. Thus we may predicate of John that he is a man, that he is one, tall, that he dwells in Kraków, that he is twenty years old, that he is rich, etc.. The particular predicates have a foundation in the perceived accidents of being that modify being in various ways.
The hierarchy of predicates (or categories) that is obtained in this way, and the subject-predicate language that is built from them, finds a basis for its legitimacy for the first time in the structure of reality. For this reason, the categories as predicates will play an indispensable role in legitimizing realistic cognition and Aristotle's entire syllogistic or logic. We may make a predication of any being with respect to "what it is in itself" (this is called essential or substantial predication), or with respect to what properties belong to it (this is called accidental predication). We may predicate of John that he is a man in view of who he is, but we may also predicate of him that he is tall, rich, etc., in view of what belongs to him. Therefore, "tall John", "rich John", "John running", and "John living in Kraków" are not different people, but one and the same "John" perceived in view of his different modifications. Moreover, there is a fundamental difference between predication about John "as a man", when we grasp in him "that which John is in his essence", and when we predicate about him and indicate accidents that belong to him but which he could lose or exchange for others, as when we predicate of him that "he is a teacher".
This distinction allows us to avoid various paradoxes and absurdities that may arise when we try to communicate what we have learned. Such paradoxes occur when we fail to perceive the difference between predication of a thing's essence (e.g., "John is a man") and predication of a thing's properties or accidents (e.g., "John has brown hair"), and so forth. The categories indicated are the basis in logic for distinguishing between accidental (praedicabile) demonstration or predication, and essential (per se) or apodeictic demonstration or predication. Accidental predication or demonstration occurs when there is a non-necessary link between the subject and the predicate, whereas essential predication or demonstration occurs when the link is necessary.
ON THE HISTORY OF THE PROBLEMATIC OF ACCIDENTS. The logical aspect of the Aristotelian interpretation of accidents was developed further by Porphyry who showed thereby the metaphysical foundations of human language. He distinguished five categories of predicates corresponding to five kinds of accidents. He defined the first three as essential accidents: genus, species and specific difference (differentia specifica). He divided the remaining accidents into "proper" (propria) and "accidental" in the strict sense.
A generic predicate predicates an essential accident "which refers to many things that are differentiated among themselves according to species, as 'animal' for example" (Isagoga, 1 a 16). A specific predicate predicates an essential accident that is predicated "of many individuals, but only such that differ among themselves only in number, not in kind" (ibid, 1 b 1). Predicates that comprehend specific accidents are such that "are predicated of many things that differ in species, where the predication does not concern the essence, but qualities" (ibid). The specific accident as such is defined as "that by which the species is richer than the genus", or as that "which is predicated of many specifically different things in order to define their qualities" (ibid, 3 b 1). However, the specific accident is not merely anything that divides things, but only that which contributes to the existence of the species and occurs in its essence. Just as matter and form produce things, so by analogy, the genus and the specific difference, namely the specific accident, produce the concept of man in the general sense. Man as a species "is composed of a genus that corresponds to matter, and a difference that is the counterpart of form" (ibid.).
Proper predicates (propria) are those which are predicated of accidents that permanently belong to the whole species or a certain part of the species. We know them because there is a two-way relation between them and the subject (the species): if something is a horse, then it neighs; if something neighs, it is a horse. Accidental predicates are those that concern properties that occur only at times and by accident. An accidental predicate is a property that "occurs and disappears without the subject perishing" (ibid., 4 a 24). Porphyry has this distinction in mind when he explains: "for example, 'animal' is a genus, and 'man' is a species; the difference is rationality, risibility, while 'white', 'black' and 'to sit' are accidents" (ibid., 1 b 1).
In the patristic period, a new aspect appeared in the way accidents were understood in connection with discussions on the attributes of God and on transubstantiation. St. Augustine in his treatise De Trinitate (V, 2, 3; PL 42, 912), calls the relations such as unity and love that occur between the Divine Persons attributes. In theology, attributes concerning God are most often formulated in negative expressions such as "indivisible", "unchanging" and "eternal".
We find a complete approach to accidents in the system of St. Thomas Aquinas. While Aquinas did not write any separate treatise on the metaphysical, logical and theological aspects of accidents, in the course of other discussions he deals with all these aspects.
Thomas' theory of accidents is based on metaphysics. Accidents are real properties in a being or substance which is their subject. In the interpretation of accidents in logic, Aquinas' theory is based on Porphyry's conceptions. Porphyry reduced all accidents to five predicates or universals. In the first case, accidents are a consequence of the nature or essence of things. In the second case they are the result of the intellect's operation.
Thomas teaches that the definition of the subject or substance always enters into the definition of the accident (In VII Metaph., lec. 1, n. 1258). This is because a being is that which has a definite existence (quasi esse habens), and an accident receives its existence together with the existence of the being which is a substance. Accidents do not exist prior to the subject or substance, nor do they exist apart from it, since the subject or substance is in a certain sense the efficient, material and formal cause of the accident (S. th., I, q. 77, a. 6, ad 2). The ontological status of an accident is best rendered by the categories of "potency" or "efficiency" than by the categories of being (ibid., III, q. 77, a. 1 ad 2). Together with the subject or substance that creates the unity of a being, accidents remain in relation to each other like potency to act and are treated as transcendental correlates (ibid., I, q. 3, a. 6). Aquinas refers to the act of creation and says that it concerns the new existence of the entire being, and so it also concerns the accidents of the being (De ent., c. VI).
With the conceptions of Ockham (14th century) and Suarez (16th and 17th century), there was a departure from the metaphysical interpretation of accidents and a return to the logical interpretation, and the logical interpretation subsequently was treated in absolute terms. An accident was no longer understood as a "being of being" (ens entis), compared with substance understood as a "being in itself" (ens in se). The real difference between accidents and the subject or substance, as well as the necessary connection between them, disappeared.
Ockham restricted all difference to the differences that occur between concrete things that we can empirically investigate in define ("non potest esse aliqua distinctio qualitercumque extra animam, nisi ubi sunt res distinctae", Summulae in libros Physicorum, I, q. 14). For this reason he rejected the reality of accidents. Furthermore, he rejected the Scotist "third nature" as existing outside the concrete thing and conceived the individual thing as an aggregate of autonomous parts which as such may be a sign, and properly speaking, a designate of plurality. Plurality is a property of that which is general. Ockham's position was that the cause of knowledge is not the object of knowledge, but the faculty of knowledge itself. For this reason he reduced everything that is general to a construct of the reason. These constructs may be natural signs (concepts) or conventional signs of things (words and names). Natural signs (concepts) exist only in the mind as general accidents (properties), and strictly speaking, as qualities. In relation to the concrete thing, they are something constructed (fictum), since they are a product of the intellect. Accidents (qualities) do not really exist, since only individual particular beings exist. The act of conception, namely the concept, "by which I know a man, is a natural sign of man, just as moans are a sign of illness, sorrow or pain, and such a sign may stand in the place of men in sentences in thought, just as a word may stand for a thing in spoken sentences" (Summa logicae, I 15). For this reason, accidents and substances are merely words that are conventional signs of speech accepted to define (or to name) the qualities of concepts and have no basis in things, and they are only the subjective constructs of the intellect.
Suarez, like Ockham, was opposed to so-called second scholasticism and thought that only that which is concrete and individual (singularia) exists. For this reason he rejected any real difference between essence and existence, and also between substance and accidents. He thought of the non-independent components of being as mere distinctiones rationis (distinctions of the mind). Everything real must have its own individual act of existence; both form and matter have their own acts of existence, both substance and accidents as well. While accidents have a diminished and infirm existence (this is the reason why they must exist within a substance), their existence is proper to them and independent — "habet suum proprium esse" (Disputationes metaphysicae, d. 31, sec. 2, 14). This view opens the road to later scientism and dualism which reduces all compositions to wholes that exist independently and are verifiable in empirical terms. In this way, the differences between substance and accidents and between the whole and its parts were eliminated. Everything that exists, exists as an individual thing. That which is not individual is an accident of quality belonging to mental acts of knowledge. Accidents as such are regarded as "modes of being" — "accidens, quod tantum est modus entis" (ibid., d. 16, sec. 1, 3). Suarez' position in the question of accidents paved the way for modern scientistic phenomenalism.
In the second period of modern philosophy, concepts such as substance and accidents as something really different were completely eliminated from the language of philosophy, and in their place philosophers spoke of primary or secondary qualities. For Descartes, thought was the original accident of the "res cogitans", and extension was the original accident of the "res extensa". When we ask about the major and original quality of substance, we are asking about that which we perceive clearly and distinctly as a thing's indispensable accident. For this reason, ultimately we cannot distinguish between a substance and its original and major accident. Thus accidents are inseparable from substances. And so, although no thought can exist without the mind, the mind can exist without any particular thought. It is the same in the case of extension: dimensions and shapes can change. Descartes called these particular qualities and accidents "modi" (Principles of Philosophy, I 56). The term was henceforth at home for good in modern philosophy. The intellect is the source of primary or original accidents and all other accidents with its measure of clarity and distinctness.
Under the influence of Descartes, Spinoza defined substance as that which exists in itself and is conceived by itself, namely that the concept of which does not require the concept of any other thing to help produce it (Ethics, I def. 3). There is only one substance, an infinite substance, and this is God. This substance possesses an infinite number of properties. Anything that exists apart from God is not, and cannot be, a substance. At most, it may be a property that manifests a modus of the existence of the Divine substance. Thus finite thoughts are modes of the existence of the substance which is God and belong to the accident of thought. Finite bodies are modes of the being of the substance-God, and as such they indicate the accident of extension (ibid., II 2). Extension and thought are primordial and primary accidents of the Divine substance, and nature as a whole is their mode. From the divine substance or nature an infinite number results — "in infinitely many ways" (ibid., I 17).
Like his predecessors, Leibniz located both substance and accidents in the sphere of ideas. We have a clear, although indistinct, idea of substance. An argument in favor of this is that "we have an inner feeling of substance in ourselves, who are substances ourselves" (Die philosophischen Schriften von G. W. Leibniz, B 1875-1890, III 247). Stability and identity are the principal properties of substance that we experience and know. We also discover substance as a substrate of which we may predicate something. However, just as predicates are contained in the concept or idea of the subject, so accidents are contained in the potentiality of the substance. Thus accidents as expressed in the language of metaphysics are nothing other than potencies (or potentialities) conceived as "powers of action" (vires agendi), with which the subject or substance is endowed, and by which one substance differs from another, that which determines the individuality and non-repeatability of a substance.
Locke rejected the idea of innate ideas and in this way prepared the way for empiricism. The mind creates all ideas either from perceptions or from reflection on the activities of the intellect (thinking, doubting, wanting, believing). Locke distinguishes primary (simple) ideas and secondary (composite) ideas. The mind passively receives primary ideas, while secondary ideas are products of its activity. Locke divided complex ideas into the ideas of substance and relation and he treated them as aggregates of simple ideas (Essay Concerning Human Understanding, Book I, ch. xxiv, par. 2; xxv, par. 6). Simple ideas are similar to bodies, while secondary ideas are not at all like bodies. Locke still distinguished ideas from accidents (or properties). An idea is anything that the mind perceives within itself. A property or accident is the power of an object to produce an idea in our mind (ibid., Book II, ch. xxxi). Accidents are also components of the idea of substance, and without them the very idea of substance would perish. Hume developed this idea further. His position was that every experience can be broken down into impressions. These impressions, when they are rightly connected and associated, provide appropriate ideas, but no real objects correspond to any other ideas. An idea such as that of substance and the modi of relations: " [t]he idea of a substance as well as that of a mode, is nothing but a collection of Simple ideas, that are united by the imagination, and have a particular name assigned them, by which we are able to recall, either to ourselves or others, that collection" (A Treatise of Human Nature, book I, part 1, sect. VI). Thus both ideas and accidents are merely subjective constructs. Their ontological status comes from memory and custom, not from a really existing object.
Kant held to a position of phenomenalism with respect to space and time. He had to accept that the whole physical world as perceived by the senses had the character of a phenomenon. For Kant, the object in critical cognition is not something that objectively exists apart from our mind, but that "in the concept of which the heterogeneity of a given mental image is gathered together". In critical cognition there are no objects without acts of thought. The subject or substance that unites accidents is not something real but a reflection of the unity of the mind and is derived from the mind. Accidents are reduced to the modi of cognitive acts, without which these properties could not be perceived. As Kant's theory of knowledge gained wide acceptance, the construction of the object and its properties began in critical thought. This kind of cognitive approach would be applied both in philosophy and in the particular sciences.
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