I understand and accept the classical argument for determinism, based on a classical understanding of the universe. Laplace used the example of a ficticious omniscient ‘angel’ who possesses:
> knowledge of the precise physical state of every particle in the universe,
> a complete understanding of the laws of the universe, and
> a vast computing power.
This angel would know, in precise detail, the entire future course of the entire universe, including the events on our planet. This knowledge of the future results from the aforementioned knowledge, plus the strict law of classical cause and effect.
(To jmullaney & aynrandlover: Note I said future events. I acknowledge that the chance of an event happening, given that it has already happened, is 100%. I’m unclear how this tautology supports determinism though.)
I’m crystal clear that this line of reasoning leads to determinism, even if there is no such angel. Laplace’s gedanken is the syllogism I referred to. The argument is akin to mathematical induction, where you prove a statement for the case n =1, and then prove that the truth of the statement for n implies it is also true for n +1.
The thing is, Laplace is 18th century and we’re now in the 21st. In the meantime, science has shown that the world at the atomic level is not classical, and classical cause and effect does not apply. Hence, Laplace’s argument is no longer valid. Another argument for determinism might be valid, but I haven’t seen it yet, and frankly, I don’t expect to see a successful argument.
Everyone is entitled to their own philosophical and religious beliefs, but I think this particular belief hinders one’s understanding of modern physics.