Aristotle’s Theory of Change and Causality
Elements of Change
Aristotle identifies three elements: the subject of change, the loss of something, and the acquisition of something new. This involves the substrate (hypokeimenon), form (morph, eidos), and deprivation (stéresis). An acorn, for example, is not an oak but has the potential to become one. Change is the actualization of this potential.
Act (entelechia or entelekheia) is the fulfillment of potential, the end to which potential is directed (teleological). Act has priority over potential, as potential is defined by its act.
Types of Changes
Substantial Change
Involves birth and death, generation and corruption, where something new emerges and something existing disappears.
Accidental Change
Refers to quantitative, qualitative, or locational changes. The substance remains the substratum of change.
To address material changes, Aristotle introduces the concept of raw material, a non-perceptible, chaotic substance.
Theory of Causes
Aristotle identifies four causes:
- Material cause: What something is made of.
- Formal cause: The essence or form of the substance.
- Efficient cause: The agent that initiates the process.
- Final cause: The purpose or reason for the process.
Aristotle posits a finite series of causes, leading to a first principle or Unmoved Mover. This Unmoved Mover is the efficient cause of motion and the final cause, a pure act of existing, a perfect entity that does not move but inspires movement as an object of desire.
Aristotelian physics is teleological, explaining nature in terms of goals and purposes. Scientific explanation must consider the final cause or telos, using expressions like “to” or equivalents to explain processes in both living organisms and inanimate objects.