The four causes are, in Aristotelian thought, categories of questions that explain "the why's" of something that exists or changes in nature. The four causes are the: material cause, the formal cause, the efficient cause, and the final cause. Aristotle wrote that "we do not have knowledge of a thing until we have grasped its why, that is to say, its cause."Aristotle, Physics 194 b17–20; see also Posterior Analytics 71 b9–11; 94 a20. While there are cases in which classifying a "cause" is difficult, or in which "causes" might merge, Aristotle held that his four "causes" provided an analytical scheme of general applicability.Lindberg, David. 1992. The Beginnings of Western Science. p. 53.
Aristotle's word aitia () has, in philosophical scholarly tradition, been translated as 'cause'. This peculiar, specialized, technical, usage of the word 'cause' is not that of everyday English language. Rather, the translation of Aristotle's that is nearest to current ordinary language is "explanation."
Overview In Physics II.3, I.7–9 and Metaphysics V.2, Aristotle holds that there are four kinds of answers to "why" questions:"Aristotle famously distinguishes four 'causes' (or causal factors in explanation), the matter, the form, the end, and the agent." Hankinson, R. J. 1998. Cause and Explanation in Ancient Greek Thought. Oxford: Oxford University Press. p. 159. . .Aristotle. Metaphysics V, (Aristotle in 23 Volumes, vols. 17–18), translated by H. Tredennick (1933/1989). London, William Heinemann Ltd. 1989 – via Perseus Project. § 1013a.
Aristotle discusses the four "causes" in his Physics, Book B, ch. 3. Matter The material cause of a change or movement. Aristotle defines matter as, "...the primary substratum of each thing, from which it comes to be per se, [substantially], and that persists in the result." - Physics I.9. Matter is what allows a thing to change, either accidentally, such as a change in shape, or substantially, such as the death of a living thing, or a compound returning to its elemental parts. Aristotle gives the examples of a table's matter being wood, or a statue's matter being bronze or marble. Form The formal cause of a change or movement. Aristotle defines form as, "...the terminus of the process of [change]." - Metaphysics V.4. It is what something changes into, i.e. what makes a thing what it is. Form is often confused with the whole substance, whereas it is a thing's essential difference, for example, man is a rational animal, what makes man a man, is his rationality, i.e. what makes him different from other animals. Efficient, or agent The efficient or moving cause of a change or movement. This consists of things apart from the thing being changed or moved, which interact so as to be an agency of the change or movement. For example, the efficient cause of a table is a carpenter, or a person working as one, and according to Aristotle the efficient cause of a child is a parent. Final cause, or end The final cause of a change or movement. This is a change or movement for the sake of a thing to be what it is. For a seed, it might be an adult plant; for a sailboat, it might be sailing; for a ball at the top of a ramp, it might be coming to rest at the bottom. Often the final cause is confused with a purpose, or intention, but this is not the case, since a purpose is the effect wanted for a thing by a person, whereas Aristotle thought of ends as always present, ungiven, and always good.
The four "causes" are not mutually exclusive. For Aristotle, several, preferably four, answers to the question "why" have to be given to explain a phenomenon and especially the actual configuration of an object.According to Reece (2018): "Aristotle thinks that human action is a species of animal self-movement, and animal self-movement is a species of natural change. Natural changes, although they are not substances and do not have causes in precisely the same way that substances do, are to be explained in terms of the four causes, or as many of them as a given natural change has: The material cause is that out of which something comes to be, or what undergoes change from one state to another; the formal cause, what differentiates something from other things, and serves as a paradigm for its coming to be that thing; the efficient cause, the starting-point of change; the final cause, that for the sake of which something comes about." For example, if asking why a table is such and such, an explanation in terms of the four causes would sound like this: This table is solid and brown because it is made of wood (matter); it does not collapse because it has four legs of equal length (form); it is as it is because a carpenter made it, starting from a tree (agent); it has these dimensions because it is to be used by humans (end).
Aristotle distinguished between intrinsic and extrinsic causes. Matter and form are intrinsic causes because they deal directly with the object, whereas efficient and finality causes are said to be extrinsic because they are external.Aristotle, Metaphysica I. 983 a26 ss. As quoted in Battista Mondin (2022), Ontologia e Metafisica, 3rd ed., ESD, p. 157, .
Thomas Aquinas demonstrated that only those four types of causes can exist and no others. He also introduced a priority order according to which "matter is made perfect by the form, form is made perfect by the agent, and agent is made perfect by the finality."Thomas Aquinas, In IV Sententiarum, d. 3, q. 1, a. 1. sol. 1. As quoted in Battista Mondin (2022), Ontologia e metafisica, ESD, 2022, p. 158 Hence, the finality is the cause of causes or, equivalently, the queen of causes.Thomas Aquinas, Summa Theologiae I, q. 5, a. 2, ad. 1
Definition of "cause"
In his philosophical writings, Aristotle used the Greek word αἴτιον (aition), a neuter singular form of an adjective. The Greek word had meant, perhaps originally in a "legal" context, what or who is "responsible," mostly but not always in a bad sense of "guilt" or "blame." Alternatively, it could mean "to the credit of" someone or something. The appropriation of this word by Aristotle and other philosophers reflects how the Greek experience of legal practice influenced the concern in Greek thought to determine what is responsible.Lloyd, G. E. R. 1996. "Causes and correlations." In Adversaries and authorities: Investigations into ancient Greek and Chinese science, Cambridge: Cambridge University Press. . The word developed other meanings, including its use in philosophy in a more abstract sense.
Aristotle, in The Metaphysics V.3, defines a cause as, "...that from which, as something intrinsic, a thing comes to be..." Some later scholastics redefined a cause as, "that from which something proceeds."
Aristotle's four causes Aristotle used the four causes to provide different answers to the question, "because of what?" The four answers to this question illuminate different aspects of how a thing comes into being or of how an event takes place.
Material
Aristotle considers the material "cause" () of an object as equivalent to the nature of the raw material out of which the object is composed. (The word "nature" for Aristotle applies to both its potential in the raw material and its ultimate finished form. In a sense this form already existed in the material: see potentiality and actuality.)
Whereas modern physics looks to simple bodies, Aristotle's physics took a more general viewpoint, and treated living things as exemplary. Nevertheless, he argued that simple natural bodies such as earth, fire, air, and water also showed signs of having their own innate sources of motion, change, and rest. Fire, for example, carries things upwards, unless stopped from doing so. Things formed by human artifice, such as beds and cloaks, have no innate tendency to become beds or cloaks.Physics 192b
In traditional Aristotelian philosophical terminology, material is not the same as substance. Matter has parallels with substance in so far as primary matter serves as the substratum for simple bodies which are not substance: sand and rock (mostly earth), rivers and seas (mostly water), atmosphere and wind (mostly air and then mostly fire below the moon). In this traditional terminology, 'substance' is a term of ontology, referring to really existing things; only individuals are said to be substances (subjects) in the primary sense. Secondary substance, in a different sense, also applies to man-made artifacts.
Formal
Aristotle considers the formal "cause" () as the internal cause by which a thing is what it is. Often, form is confused with what Aristotelians call accidental form, i.e. what makes an inhering part what it is. Some say that form is the arrangement or shape of a thing, but this is not the case, since Aristotle would define these things as accidents, (falling under quality and position, respectively), while he defines form as the principle of a substance. This mistake is made because, with some things, what makes them what they are is their accidents. These things are called accidental beings. For things such as a three-legged stool, what makes it what it is is the number of legs it has, which is a quantity. But for other things, such as a bowl, if defined as a tool which has the ability to hold liquids, what makes it what it is is not its shape, but its ability to hold liquids, since its shape could change, and it could still have its ability.
By Aristotle's own account, this is a difficult and controversial concept. It links with theories of forms such as those of Aristotle's teacher, Plato, but in Aristotle's own account (see his Metaphysics), he takes into account many previous writers who had expressed opinions about forms and ideas, but he shows how his own views differ from them.Lloyd, G. E. R. 1968. "The critic of Plato." pp. 43–47 in Aristotle: The Growth and Structure of His Thought. Cambridge: Cambridge University Press. .
Efficient
Aristotle defines the agent or efficient "cause" () of an object as that which causes change and drives transient motion (such as a painter painting a house) (see Aristotle, Physics II 3, 194b29). In many cases, this is simply the thing that brings something about. For example, in the case of a statue, it is the person chiseling away which transforms a block of marble into a statue. According to Lloyd, of the four causes, only this one is what is meant by the modern English word "cause" in ordinary speech.
Final
Aristotle defines the end, purpose, or final "cause" () as that for the sake of which a thing is done. Like the form, this is a controversial type of explanation in science; some have argued for its survival in evolutionary biology, while Ernst Mayr denied that it continued to play a role."The development or behavior of an individual is purposive, natural selection is definitely not…. Darwin 'has swept out such finalistic teleology by the front door.'" It is commonly recognized that Aristotle's conception of nature is teleological in the sense that Nature exhibits functionality in a more general sense than is exemplified in the purposes that humans have. Aristotle observed that a telos does not necessarily involve deliberation, intention, consciousness, or intelligence:Barnes, Jonathan, ed. The Complete Works of Aristotle, vol. I. The Revised Oxford Translation.