Aristotle described four types of cause: material, formal, efficient and final [1]. Using the examples of a building and a person, this what the four types mean and how they relate:

Material cause: that from which something is made: its material.
building: concrete, bricks, steel and wood.
human: carbon-based elements.

Formal cause: that into which something is made: its form.
building: the blueprints.
human: our DNA

Efficient cause: that by which something is made: its means.
building: the builders
human: our parents.

Final cause: that for which something is made: its purpose.
building: to shelter people.
human: to worship God and enjoy Him forever [2].

Consider the question, “Why does X happen?” The question “why”, here can have two meanings, depending on how it’s used. In its traditional sense, it refers to the purpose of the subject. But “why?” can also be used to refer to the means by which something happens. In this case, the question should be phrased (crudely, in a simple substitution of interrogatives) “How does X happen?”, or better, “What makes X happen?”

In practical terms, the question “Why does an apple fall?” isn’t as simple as it first seems. For our purpose, there are two ways the question could be nuanced: “why does an apple fall?” and “why does an apple fall?”

The first nuance, “why does an apple fall?”, could have two interpretations. The first interpretation relates to the means (the efficient cause) by which the apple falls. What changes the apple from a hanging state to a fallen state? In other words, what makes an apple fall? This is a question science can answer. It becomes over-ripe and too heavy for its stem.

The second interpretation of the question relates to the purpose (the final cause) of the apple. What is the reason that the apple falls – what’s it all about? There are two answers: to be eaten, and/ or to grow other apple trees. This, of course, leads to the question, “why do apple trees grow in the first place?” The list of final-cause questions continue, as we saw, back to the ultimate final-cause question: “why did life start in the first place?”

The second nuance, “Why does an apple fall?”, relates to the behaviour of the apple: why doesn’t it just hang there, or float upwards? Like the first nuance, this has two interpretations. Also like the first nuance, the two interpretations relate to the efficient cause (means) and to the final cause (purpose), respectively. The answer to the latter is, of course, the same. The answer to the first, studied by the scientific method, comes to us courtesy of Isaac Newton: gravity.


[1] Much of the material for this section came from three articles in the 2007 edition of the Encyclopaedia Britannica: “Aristotle” and “Metaphysics”; and “Cause, Causation”.
[2] According to the Westminster Confession of Faith.

copyright Troy Grisgonelle 2007.