Aristotle describes and argues for the four causes in his books Physics and Metaphysics as a part of developing his philosophy of substance. He claims that there are four causes (or explanations) needed to explain change in the world. A complete explanation of any material change will use all four causes. These causes are material, formal, efficient and final.
The material cause is what something is made out of. The human body of made up of cells. Wooden boxes are made up of wood. Computers are made out of transistors and other electronic components. The material cause also explains the general sort of properties of something. Wooden boxes burn because they are made out of wood. The human body needs oxygen because its cells need oxygen. Finally, the material cause can be divided into two: prime matter and proximate matter. Proximate matter is matter that has some properties, such as wood, cells and electronic components. Prime matter has no properties at all. Aristotle believed that prime matter did not exist, but was theoretically necessary.
The formal cause is what makes a thing one thing rather than many things. The human body is human, wooden boxes are boxes, and computers are computers. The difference between a mere collection of cells and a human body is that a human body has properties and functions that come from a particular arrangement of the right kind of cells doing the right kind of things. A mere collection of cells is not the formal cause. A human body is the formal cause. The formal cause can also be divided into two: formal cause and exemplary cause. An exemplary cause is the plan in someone’-s mind that gave rise to a computer. Things have either a formal cause or an exemplary cause –- not both.
The efficient cause is what did that. If a ball broke a window, then the ball is the efficient cause of the window breaking. Every change is caused by an efficient cause. If your eye sees, then it sees because light from the object strikes your eyes and causes you to see what is there. Efficient causes answer the what did that question, but do not answer how it was done.
The final cause is why efficient causes do what they do and why formal causes do what they do. Why do balls break windows? The final cause says that because balls are hard and windows are brittle, they break. Why do rocks fall? Aristotle said that rocks fall because they are heavy. Air is light, therefore air rises. These are all pointing out the final cause of efficient causes. To ask for the final cause of formal causes is to ask why these things exist at all. Why do human beings exist? Aristotle says that they exist to make more human beings, because they are alive. They also exist to be happy because they are rational. Why pressure cookers exist? They exist because people made them. They wanted to use them as a tool in cooking. Why do rocks exist? They exist because the wind, sea and rain break rock formations to produce rocks. These things are also final causes.