In that sense the behavior of light in this apparatus is deterministic, but there is no way to predict where in the resulting interference pattern any individual photon will make its contribution (although, there may be ways to use weak measurement to acquire more information without violating the uncertainty principle). Some (including Albert Einstein) have argued that the inability to predict any more than probabilities is simply due to ignorance. The idea is that, beyond the conditions and laws can be observed or deduced, there are also hidden factors or "hidden variables" that determine absolutely in which order photons reach the detector screen. They argue that the course of the universe is absolutely determined, but that humans are screened from knowledge of the determinative factors. So, they say, it only appears that things proceed in a merely probabilistically determinative way. In actuality, they proceed in an absolutely deterministic way. John S. Bell criticized Einsteins work in his famous Bells theorem, which, under a strict set of assumptions, demonstrates that quantum mechanics can make statistical predictions that would be violated if local hidden variables really existed. A number of experiments have tried to verify such predictions, and so far they do not appear to be violated. Current experiments continue to verify the result, including the 2015 "Loophole Free Test" that plugged all known sources of error and the 2017 "Cosmic Bell Test" experiment that used cosmic data streaming from different directions toward the Earth, precluding the possibility the sources of data could have had prior interactions.
Immaterial souls exist, but exert no causal influence, free or determined (epiphenomenalism, occasionalism)
Immaterial souls do not exist – there is no mind-body dichotomy, and there is a materialistic explanation for intuitions to the contrary. With ethics and morality
Another topic of debate is the implication that determinism has on morality. Philosopher and incompatibilist Peter van Inwagen introduced this thesis, when arguments that free will is required for moral judgments, as such:
The moral judgment that X should not have been done implies that something else should have been done instead. That something else should have been done instead implies that there was something else to do. That there was something else to do, implies that something else could have been done. That something else could have been done implies that there is free will. If there is no free will to have done other than X we cannot make the moral judgment that X should not have been done. History
Determinism was developed by the Greek philosophers during the 7th and 6th centuries BCE by the Pre-socratic philosophers Heraclitus and Leucippus, later Aristotle, and mainly by the Stoics. Some of the main philosophers who have dealt with this issue are Marcus Aurelius, Omar Khayyám, Thomas Hobbes, Baruch Spinoza, Gottfried Leibniz, David Hume, Baron dHolbach (Paul Heinrich Dietrich), Pierre-Simon Laplace, Arthur Schopenhauer, William James, Friedrich Nietzsche, Albert Einstein, Niels Bohr, Ralph Waldo Emerson and, more recently, John Searle, Ted Honderich, and Daniel Dennett.