Aristotle on causality

Causality is one of the most hotly debated topics in  philosophy (contemporary and historical). Aristotle’s thoughts on causality are a product of his grander musings on the nature of change. He produced a scheme of four fundamental (or irreducible) causes which he believed were required to fully understand an object and any change it may undergo. I will briefly outline these four causes and following that I will contrast Aristotle’s thoughts to those of Democritus (and by extension the philosophy of modern mechanism).

Material cause: the material of which an objects consists (i.e. wood for a table or air for wind).

Efficient cause: is the primary cause of the change or rest and was often associated with motion by Aristotle (i.e. for a cliff the efficient cause may be the wind or ocean).

Formal cause: the formal cause is what makes matter into the type of thing the object is. Remember that although Aristotle undoubtedly inherited the concept of forms from his teacher Plato, his own ideas were quite different. For example, the form of tree-ness (which inheres in the tree) is the cause of the matter arranging in a tree-like fashion.

Final cause: is the goal or end of the object. For example, the end of a seed is to produce its tree or plant. Aristotle argues that the final cause is the most important of all causes in his Physics thusly: “if one defines the operation of sawing as being a certain kind of dividing, then this cannot come about unless the saw has teeth of a certain kind; and these cannot be unless it is of iron.” Under this hierarchy, the final cause or end of the object determines the other causes.

Democritus would naturally approve of the first two causes. His material cause would be atoms (of various shapes and sizes) and his efficient cause would be motion. However, Aristotle’s notion of formal and final causality is incompatible with Democritus’ atomism; to understand why the important distinction between necessary and sufficient causes needs to be understood.

For example, if one were to ask Democritus why rain falls and tress grow leaves he would say that it is necessarily so. When water rises into the atmosphere it must cool and condense into droplets and fall back to earth. As a tree grows it must grow leaves and so on. It happens as it does because it cannot be any other way. In this way Democritus is a determinist with a neccessitarian view of cause and effect.

Aristotle counters in true Socratic fashion:

Democritus, however, neglecting the final cause, reduces to necessity all the operations of nature. Now they are necessary, it is true, but yet they are for a final cause and for the sake of what is best in each case. Thus nothing prevents the teeth from being formed and being shed in this way; but it is not on account of these causes but on account of the end…

– Aristotle, Generation of Animals

Aristotle asks why does the water vapour not simply fly out into space and why do trees not grow basketballs instead of leaves? He says it is because there is an end or goal involved (i.e. final cause). The rain falls back to the earth to nourish the crops and the trees grow leaves for photosynthesis. For Aristotle, there are both necessary and sufficient causes. Aristotle’s concept of final causality is related to his ideas about goodness, which I will examine in a later post.