Change and Causality in Aristotelian Philosophy
Aristotle’s Analysis of Change
The problem of physics is to explain change, because change is inherent in nature. Aristotle believed that prior philosophers had failed to adequately explain change. He then analyzed why other philosophers failed to explain kambia (change).
- Some said that everything flows, that reality is pure movement. But this did not explain the nature of change itself.
- Others, like Parmenides and Plato, denied change. Parmenides said kambia is when something goes from not-being to being (birth) or when it goes from being to not-being (death). Plato said that kambia belonged to the world of shadows and, therefore, was not subject to knowledge.
Aristotle distinguishes four types of change:
- Substantial Change: The most radical change, where something is born or dies.
- Quantitative Change: The amount of something increases or decreases.
- Qualitative Change: The quality of something changes.
- Local Change: Something is rearranged or changes location.
Aristotle defined change as the transition from potentiality to actuality, which necessarily occurs through a cause. For example, how can a chicken come from an egg? Aristotle’s explanations are based on potentiality and actuality. Being is potentially able to become, and change means developing a potential.
Consequences: The Prime Mover
This explanation of change required a cause (kausa) that must satisfy the following conditions:
- It must be in act.
- It must not be the same as the moved object.
- It must be in contact with the moved object.
This led to several consequences in physics and metaphysics:
- In physics: The example of the arrow.
- In metaphysics: Aristotle’s conception led to the existence of a First Mover (God), since everything that moves is moved by something else. Therefore, there must be a first kausa. Aristotle’s physics culminated in the idea of the First Mover, which must be immutable and move everything else without being moved. It must be pure act, cannot have potential, and cannot move because that which is in potentiality can be moved. But in the universe, all movement is by contact, and to be in contact, something must be material.
The Theory of Causality
Any change needs a cause, as all science is a causal explanation. Aristotle proposed the first theory of causation, which would be criticized and abandoned in the modern age. According to Aristotle, there are four types of causes:
- Material Cause: The matter of which a phenomenon is made.
- Formal Cause: The model or form of this phenomenon; this idea came from Plato.
- Efficient Cause: The necessary condition for this phenomenon to arise.
- Final Cause: The end or purpose of the phenomenon; this idea also appears in Plato, whose ultimate cause was the highest good.
The scientist should look for all four causes. For Aristotle, the most important cause is the final cause, and any change must have an end. However, modern physics focused on the efficient cause and disregarded the others. The final cause (the most important for Aristotle) was abandoned because:
- Modern physics is mathematical, studying quantitative aspects, and the final cause cannot be measured (it is qualitative).
- The concept of a final cause implies the existence of God, and modern science wanted to be separated from religion.
- The final cause involves the idea that things are substances with an essence, but modern physics is only interested in explaining the workings of the cosmos, not in seeing its beauty or finding a purpose.