What is Cause?
The theories of the pre-Socratic philosophers postulated the elements from which all things were formed: earth, air, fire, and water. This view corresponds somewhat to Aristotle's concept of a material cause; however, it was too limited to account for an ordered cosmos and its intelligibility.
Plato's concept of the causes of things in part resembles Aristotle's formal cause. In his treatment of the problem, however, Plato made the mistake of treating the essences of entities (the Platonic Forms or Ideas) as though they were substances in their own right.
The Four Causes
Aristotle found unacceptable Plato's view that the essence of entities resides in a separate realm of Forms. He attempted to describe the existence of all things in terms of the things themselves, without postulating a special metaphysical realm. According to Aristotelian analysis, all material things (sensible substances) are composed of matter and form. Matter, or the material cause, is the "stuff" of which a thing is made - brick is the material cause of a house. It is important to note here that "matter" is a relative term for Aristotle; by it he means the materials of a thing relative to the structure that holds them together. Thus, the elements are the material cause of tissues; tissues are the material cause of organs; and organs are the material cause of the living body.
The form of an entity, either its "shape" or its structural plan, is its formal cause. The blueprint, or the actual structure of a house, are the formal causes of the house. The formal and material causes are generally inseparable for Aristotle-each requires the other.
Although each individual entity is a composite of matter and form, these two categories do not sufficiently account for why things are what they are. There must be an agent or force that imposes the form on the matter. That something is Aristotle's efficient cause, the vis a tergo, or "push from behind." The builder of a house (or the builder in the act of building) is the efficient cause of the house. This cause most closely corresponds to the ordinary meaning of "cause" today.
Just as the "push from behind" pushes the substance to change in a specific direction, that direction is predetermined by the vis a fronte, or "pull from the front": the entelechy, or final cause. This cause is the end, purpose, or goal at which the process of change aims and terminates. The final cause of a house might be "being comfortable to live in."
The Aristotelian account of causation is not generally used in modem analysis of cause, which is interested in clarifying statements concerning cause in ordinary and scientific discourse. However, the subject of final causes (teleological explanation) is still vigorously discussed, particularly in the life and social sciences. See also causality.