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No, Determinism in Nature Has Not Been Demonstrated Scientifically

Michael Egnor


Jerry Coyne is a professor of evolution at the University of Chicago. He has written extensively about his denial that we have libertarian free will. I have pointed out several times the incoherent and even self-refuting nature of his claims. I’ll take this opportunity to consider a few things that he gets very wrong in his arguments. For the moment I’ll focus on his assertion that determinism is true and therefore that free will can’t be true. I’ll follow up later, discussing his denial of the immateriality of the mind and about the self-refuting nature of denial of free will.

Coyne asserts that determinism in nature has been demonstrated scientifically. He is wrong; the opposite has in fact been demonstrated. A little background will help.

In the wake of the Newtonian revolution, Pierre-Simon Laplace in the 19th century famously asserted:

We may regard the present state of the universe as the effect of its past and the cause of its future. An intellect which at a certain moment would know all forces that set nature in motion, and all positions of all items of which nature is composed, if this intellect were also vast enough to submit these data to analysis, it would embrace in a single formula the movements of the greatest bodies of the universe and those of the tiniest atom; for such an intellect nothing would be uncertain and the future just like the past would be present before its eyes.

That deterministic view — the view that nature was a huge machine in which every state of affairs was entirely determined by the immediately preceding state of affairs and the laws of physics — held sway well into the 20th century.

It wasn’t until the advent of quantum mechanics that physical determinism came into question. It became apparent that deterministic "mechanical" physics was inadequate to describe the subatomic world, and that in fact indeterminism seemed to be the most successful way to describe nature. Macroscopic nature seemed deterministic in some ways, but a closer look on the atomic scale suggested that determinism was an illusion.

Neils Bohr and Albert Einstein debated determinism over the early decades of the 20th century. Bohr doubted determinism. Einstein defended it. There seemed to be no way that the issue could be settled decisively by experiment.

In 1964, John Bell, an Irish physicist, pointed out in a paper entitled "On the Einstein-Podolsky-Rosen Paradox" that there was a way that the determinism/indeterminism question could be answered experimentally. His experimental design involved a pair of detectors and the measurement of the spin of entangled subatomic particles (Brian Green in his superb The Fabric of the Cosmos has a lucid description of the details and results of the experiments). The actual experiments were conducted in 1972 and repeated many times over the ensuing decades. The results are unequivocal and accepted by essentially all physicists working in the field. There are no "local hidden variables," which means that quantum processes are indeterminate, at least locally. The remote possibility of the existence of non-local hidden variables remains open (they are not encompassed by Bell’s theorem), but most physicists believe they are unlikely to exist and that indeterminism is proven.

Determinism is dead in physics, and has been dead for decades. �

Yet Coyne bizarrely repeats his mistake — he insists that determinism in physics is true, and he seems completely unaware of the consequences of Bell’s theorem and of the unequivocal experimental evidence that nature is not deterministic. And this mistake is much of the foundation on which Coyne’s denial of free will rests.

Coyne seems to have a proclivity for outdated 19th-century science and for the materialist metaphysics from which these mistakes arise.

Image: By Antonia Daniel (originally posted to Flickr as Jerry Coyne) [CC BY-SA 2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons.