Causality is the belief that a second event is the consequence of a first event. This is usually described as a relationship between a cause (first event) and an effect (second event).¹ Not everyone sees causality as a belief. But from a mature philosophical perspective, that’s exactly what it is.
The ancient Greek philosopher Aristotle saw causality in terms of four interrelated causes or explanatory factors:
- The material cause: The raw material used to make an object (e.g. wood)
- The formal cause: What the object will be (e.g. a chair)
- The efficient cause: How the object is created (builder)
- The final cause: The object’s function or purpose (it is used for sitting)
This teleological perspective is based on Aristotle’s belief that a valid distinction can be made between a thing’s essence and its observable form.²
Perhaps in keeping with Aristotle’s idea of a “formal cause,” Michelangelo said that, when sculpting, he simply removed the stone that hid the figure already existing within.
The idea of one event causing another event has been critically examined. The philosopher David Hume suggested that the idea of causality is nothing more than an expectation based on past experience and human limitations.
Hume’s critique of the belief in cause and effect challenges our conventional way of seeing. All we can be sure of, says Hume, is that certain events occur one after another in a given region and for a certain duration.
In billiards, for instance, the white ball appears to cause the motion of other balls when impacting them on the gaming table. But here’s the radical part. Hume says that all we can truly know is that, in the past, the first ball impacted and the other balls moved. We cannot prove that the first ball’s impact will always be followed by movement of the other balls. And for Hume, there is no rational way to demonstrate a causal connection:
Reason can never shew us the connexion of one object with another, tho’ aided by experience, and the observation of their constant conjunction in all past instances. When the mind, therefore, passes from the idea or impression of one object to the idea or belief of another, it is not determin’d by reason, but by certain principles, which associate together the ideas of these objects, and unite them in the imagination.³
Put differently, from prior experience we build up a series of expectations and habitual ways of interpreting observations. Hume calls these “ideas.” But ideas they simply are. Although we expect the billiard balls to move, we have no way of proving or knowing that they always will.
At first, this may seem absurd. But Hume’s critique of causality had a profound effect on one of the most important thinkers in the history of Western philosophy, Immanuel Kant. Mortimer Adler says “…Kant tells us that David Hume awakened him from his dogmatic slumbers.”4
In addition, developments in subatomic physics, especially concerning particle reaction chambers, have challenged many longstanding assumptions about causality. On a quantum level of reality, contemporary physicists claim that observations of subatomic particles support the ideas of probability and simultaneity instead of linear causality.5
¹ Wikipedia gives a standard definition that most would accept: http://en.wikipedia.org/wiki/Causality
³ David Hume, A Treatise of Human Nature (1896 ed.), SECTION VI.: Of the inference from the impression to the idea, paragraph 278.
4 Adler, Mortimer J. (1996). Ten Philosophical Mistakes. Simon & Schuster. p. 94, cited at http://en.wikipedia.org/wiki/Critique_of_Pure_Reason#cite_note-2
5 Some argue, however, that it’s invalid to compare quantum and macroscopic levels of reality because subatomic particles exist in an entirely different arena, and behave in different ways than the larger aggregate objects which they make up.
On the Web:
- The Problem of Induction (plato.stanford.edu)
- David Hume and the Theatre of the Mind (exploringphilosophy.wordpress.com)
- Quantum causal relations: A causes B causes A (eurekalert.org)
- Causation Warps Our Perception of Time (psychologicalscience.org)
- David Hume’s final moments (person) (everything2.com)