The Axiom of Causality is the proposition that everything in the universe has a cause and is thus an effect of that cause. This means that if a given event occurs, then this is the result of a previous, related event. If an object is in a certain state, then it is in that state as a result of another object interacting with it previously.
According to William Whewell the concept of causality depends on three axioms:
A similar idea is found in western philosophy for ages (sometimes called Principle of Universal Causation (PUC) or Law of Universal Causation), for example:
Modern version of PUC is connected with Newtonian physics, but is also criticized for instance by David Hume. Since then his view on the concept of causality is often predominating (see Causality, After the Middle Ages). Kant opposed Hume in many aspects, defending the objectivity of universal causation (see: Causal thinking).
Example for the axiom: if a baseball is moving through the air, it must be moving this way because of a previous interaction with another object, such as being hit by a baseball bat.
An epistemological axiom is a self-evident truth. Thus the "Axiom of Causality" implicitly claims to be a universal rule that is so obvious that it does not need to be proved to be accepted. Even among epistemologists, the existence of such a rule is controversial. See the full article on Epistemology.
One implication of the Axiom is that if a phenomenon appears to occur without any observable external cause, the cause must be internal. See Compatibilism.
Another implication of the Axiom is that all change in the universe is a result of the continual application of physical laws.
If all events are cause and effect relationships that follow universal rules, then all events—past, present and future—are theoretically determinate. See Causal determinism.
If all effects are the result of previous causes, then the cause of a given effect must itself be the effect of a previous cause, which itself is the effect of a previous cause, and so on, forming an infinite logical chain of events that can have no beginning. See the cosmological argument.