Determinism is a philosophical doctrine that holds that all physical events, including human thought and actions, are causally determined by the unbreakable chain of cause-consequence and, therefore, the current state in some sense "determines" the future. There are different formulations of determinism, differing in the details of their claims. There are three types of determinism.
Logical determinism holds that the truth value of any proposition is timeless. For example: the sentence "Tomorrow it will rain" is true or false, and if it is true, then tomorrow it will rain by logical necessity.
Epistemic determinism holds that if any future event is known in advance, then that event must inevitably occur.
Causal determinism holds that all events are the result of natural laws and preceding conditions.
To distinguish the different forms of determinism, it is convenient to classify them according to the degree of determinism they postulate:
Strong determinism holds that there are no genuinely random or chance events and that, in general, the future is potentially predictable from the present. The past could also be "predictable" if we know perfectly well a specific situation in the chain of causation. Pierre-Simon Laplace defended this type of determinism.
Weak determinism holds that it is probability that is determined by present events, or that there is a strong correlation between the present state and future states, even allowing for the influence of essentially random and unpredictable events.
It should be noted that there is an important difference between determination and predictability of events. Determination exclusively implies the absence of chance in the cause-effect chain that gives rise to a specific event. Predictability is a potential fact derived from the accurate determination of events, but it requires that the initial conditions (or any point) of the causal chain be known.