For many determinists their vision of the world and of their place in it is what we might call Laplacian, after the great physicist Pierre Laplace. In his Essai philosophique sur les probabilities, Laplace argued as follows:

The future state of the universe, including of those entities in it who fancy themselves as free agents, is entirely predictable because it is fixed once initial conditions are established. Everything unfolds in accordance with the laws of nature. An omniscient being – Laplace's oddly named (but not by Laplace) Demon – could predict what would happen to me and how I would behave long before I had any idea of either of these things. As Peter van Inwagen has put it, “there is, at any instant exactly one physical possible future”. The idea of my exercising choice – and hence choosing between one future and another – is fantasy.

As we shall see, the “intelligence” to which Laplace referred, the demon, has no place in the Laplacian universe. Nor would Laplace himself, the discoverer of his eponymous law, be accommodated in the law-bound world picture he offers in the passage we have quoted. But we are getting ahead of ourselves.

And then there is causal necessity. Is it not true that my actions – material events arising in a material body – are the effects of prior causes whose ancestry precedes my being born, stretching back, perhaps, to the Big Bang?

Thus, a double whammy for any claim to true agency, to my being a genuine source of my actions, shaping my own future and that of at least a small part of the universe.