Some determinists argue that all physical events are not only law-governed but also the inescapable effects of prior events – their causes. Since behaviour must take place in, and make a difference to, the physical world, the idea of actions as a metaphysically privileged category of happenings expressing an agency free from the bondage of causation is therefore fantasy. Even when actions are motivated by “internal events” such as explicit intentions, beliefs, hopes, or the idea of an immediate or distant goal, so the argument continues, they are no less determined from without. Internal events are the effects (and subsequently causes) of external events.

Intentions, reasons, wishes and such-like are simply intermediate (presumably physical) causes located between physical inputs understood as stimuli and physical outputs understood as responses. These intermediaries have either been implanted as biological instincts or “drives”; or they are the consequences of cultural conditioning, the latter being rooted in biology and hence ultimately in the physical world. Even when we do exactly as we want we are not acting freely because we have not chosen the wants that cause our actions. Those wants have a causal ancestry that ultimately lies outside of us.

In short, actions are part of the natural order and are themselves natural phenomena. This is necessary if they are to interact on level terms with the rest of the natural world. The movement of the arm of a person who picks up a stone to throw it is, and must be, as subject to Newton's laws as is the flight of the stone and what happens when the stone falls to the ground.