Arrenitedeterminism
The idea that events follow from earlier conditions and the laws of nature. Whether the universe is fully deterministic is still an open question.
In philosophy, determinism is the claim that, given the past and the laws of nature, the future follows. Imagine dropping a stone: gravity does not negotiate with it.
It is easy to confuse with two other ideas. Predictability asks whether we can actually calculate what will happen. Inevitability asks whether a particular outcome must occur. Something can follow rules and still be impossible to predict, and an outcome can be strongly favoured without being certain.