On Aristotle’s Four Causes

It is a commonly heard refrain in our day, particularly among so-called “analytic” philosophers, that a causal account of the cosmos is futile and irrelevant. We find this idea most famously propounded in the writings of Galileo, Descartes, and Newton. In particular, the fourth cause, or the “teleological” cause is the most controversial and detrimental to modern natural philosophy in its efforts to unveil the hidden truths of nature, not simply for the sake of knowing, but also in order to serve the needs of mankind, or as Francis Bacon put it, to “relieve the estate of man.” This is a wholly different project from the classical inquiry into nature found in Aristotle. In fact, modern natural philosophy self-consciously reacts against the authority of Aristotle, whose natural philosophy can best be found in his Physics and Metaphysics. In order to better orient ourselves to this modern revolution in physics, we must first turn to the classical example in Aristotle.

In Book II of Aristotle’s Physics (Greek for “nature” or “things in motion”), we receive the classical understanding of nature and its four causes. In Aristotle, all things of have being, and of the things that are, there are those that exist of their own nature, like animals and plants and so on, and things that exist by causes, like a house or a chair. Nature in Aristotle is “a certain source and cause of being moved and of coming to rest in that to which it belongs primarily, in virtue of itself and not incidentally” (192B 20-30), like a doctor healing himself. We moderns tend to refer to nature as the sum of all things, however Aristotle refers to nature as: the source of what governs the unique pattern of activity for each thing.

Now, the term “nature” is also used to discover or understand the underlying essential characteristic of a thing, or the “thinghood” of something. And this nature is determined by the way a thing has in itself the source of motion or change, and in another way in speech, the thing has a “form” or “look,” which is the quest of discovery embarked upon frequently in the Platonic corpus. This form or look is more akin to a thing’s nature since it is the thing fully at work (i.e. being-at-work-staying-the-same) while its material is merely potentiality (for a further discussion on this distinction see Aristotle’s Metaphysics). What is a thing that grows? Not from which, but into which it grows, therefore nature is the form or look of a thing (eidos). However, objects or things in motion contain both form as well as material.

Why do we, then, need to learn about causes (atias)? Can we not take the advice of our modern scientists that causal inquiries are futile? In Chapter 3 of Book II, Aristotle answers. We investigate causes for the sake of knowing (episteme) because we do not think we know a thing unless we grasp the “why” of its coming into being and passing away and every other change. There are four types of these questions.

First, the Material Cause: out of which something comes to be. This cause echoes the discussion of material in Book I chapter 9, as material is something deprived of and stretching out toward its form. For example: the material cause of a chair is wood.

Second, the Formal Cause: the form of something provides orderliness, the look disclosed in speech, and the ultimate source of anything that is being-at-work. The form is anything stretching out to achieve its highest attainable perfection. For example: the formal cause of a chair is the shape and ideal structure of a chair that comes to mind when someone communicates the word “chair.”

Third, this cause has been called the Efficient Cause, though this is hardly true to the original Aristotelian text. This cause stands at the start of a causal chain of responsibility. For example: an efficient cause of a chair might be a builder who cut down a tree and started cutting up the wood.

Fourth, the best example of an efficient cause, is the Teleological Cause, which is the completion or end for the sake of which anything happens. Animals act for the sake of their offspring, gardens are planted so that humans may eat food. For example: the final cause of a chair might be something to sit down on. All natural beings act as a whole and thus fulfill certain deficiencies and potencies by acting with purpose. The Final Cause also governs the Formal Cause, and thus teleology is the characteristic of all nature, however nowhere in Aristotle do we find human beings stamping their final causes onto nature, as some would later criticize of Aristotle. This leads Aristotle into a fascinating discussion about chance and necessity in the following chapters.

Aristotle says that causes are spoken about in many ways, and can, at times, overlap or blend in with one another. The idea of a wholly causal cosmos leads Aristotle to famously reason, later in Book VIII, that there must be prime cause, or a “motionless first mover,” or an unmoved mover who is separate and indifferent to all later causes (echoing Plato’s Timaeus). Like Plato, Aristotle acknowledges the irrationality of suggesting there was a first beginning of time before the existence of time and motion. Thus the beginning could only have happened in a temporal sense.

Some aspects of motion are sudden and unpredictable, like an animal suddenly awakening from a sleep. Why couldn’t nature, itself, work this way? The modern physicist, following from Galileo, sees mathematics superimposed over nature, or rather that nature is written in the language of mathematics. And mathematics is dependent upon the idea of “space,” translated from the look of geometry to the physical “place” where beings in motion reside. In contrast, Aristotle begins in the realm of “place” with beings-at-work and reasons about them by means of causes. The Physics answers the question of “how” we might come to know about beings at work and in motion in nature – namely we may look to causes for knowledge of natural philosophy. But the Physics embarks on an inquiry that may only lead us, in the end, to the doorstep of “first philosophy,” namely the Metaphysics, which asks the fundamental question of thinghood.


For this reading I used Joe Sachs’s illuminating and literal translation, Aristotle’s Physics: A Guided Study (Masterworks of Discovery).

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