A Summary of Book 2 of Aristotle's "Physics"

by Danny Djeljosevic
Aristotle is one of the major figures of Western philosophy.

Aristotle is one of the major figures of Western philosophy.

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Written in the fourth century B.C.E., Aristotle's "Physics" is a work consisting of eight books that discusses philosophy as it relates to the surrounding world. By examining physical objects and their place in the world, Aristotle discusses the reasons why events happen and why objects exist. In Book 2 of "Physics," Aristotle looks at the definition of nature, the various causes that work together to incite change and how nature itself fits in with those causes.


Aristotle begins Book 2 by discussing the use of the word "nature," which he defines in two ways, using the example of a wooden bed to clarify his point. First, he identifies "nature" as the matter constituting an object and that matter's ability to change forms. According to this definition, the nature of the bed is its wood. His second, more commonly used definition of nature is the object's form. For this definition, the nature of the bed would be its shape, with legs and a flat area to lie down on. To further explain his stance on "nature," he comes up with the theoretical scenario of burying the bed in the ground, focusing on what would actually grow from the burial. He believed more wood in the form of a tree would theoretically grow, not more beds. Therefore, to Aristotle, the nature of the bed is wood.

Nature and the Sciences

Aristotle shifts his attention to academics, contrasting mathematics and physics as studies that separately address a different definition of "nature." To Aristotle, mathematics is the study of his "form" definition of nature. Conversely, physics seeks to evaluate the "matter" definition of nature. Aristotle suggests that academics should study both senses of "nature" to get a more well-rounded view of the world.


Aristotle continues his discussion by going over the idea of "causes" to explain why an object changes. Aristotle comes up with four causes: the material an object is made of, like the bronze in a bronze statue, the form or characteristics of the object, such as the planning or structure, the specific source of change, such as a father in the creation of a child, and the basic "why" behind the change occurring, such as a person's desire to be healthy.


Aristotle introduces chance into the discussion, a factor that comes into play when events are accidental, happening without any specific intention. For example, two people running into one another at a market doesn't happen because they want to meet. Rather, it happens because they wish to be at the market for different reasons. Aristotle differentiates between the similar concepts of chance and spontaneity. To Aristotle, chance occurs when a being acting has conscious thought like a human whereas spontaneity occurs when animals, inanimate objects and very young children are acting without conscious intention.

Nature, Art and Necessity

In the final sections of "Physics" Book 2, Aristotle compares nature and art, meaning the act of creating artificial objects. Basically, if humans create objects for a purpose, and art imitates nature, then nature must logically act for a purpose. To support this flawed thesis, which ascribes intentionality to nature, he uses examples such as rain falling down to keep crops alive.

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