Most reactions I have received to my article of April 20, 2012, were meant to reassure me that there was no reason to doubt the existence of free will, because Laplace’s unbroken chain of cause and effect had not survived the advent of quantum mechanics in the twentieth century. In classical physics, every phenomenon had a cause with an irreversible effect, but we now know that subatomic particles move in reversible quantum processes, which does away with the link between cause and effect.

My attention was also drawn to the development of existential phenomenology, which counteracted the concept of a reductionist universe that obeyed the law of entropy. The development of negative entropy (‘negentropy’) had shown that causal explanations did not suffice any longer.

From this brief summary it must be clear that I am too much a layman in this field to express any useful reaction, but before tentatively reverting to existential phenomenology anyway, there is one point I would like to make. No one has commented on the distinction I make in my article between the two separate questions of (a) whether the future is predetermined and that of (b) whether it is predictable. Laplace’s definition has often been dismissed on account of the future’s being unpredictable. I think that is unfair to Laplace. In his postulate he makes it abundantly clear that he knows full well that his hypothetical intellect does not exist and will never exist. But if it existed, it would know the past and the future, provided everything happened, as Laplace postulates, according to a unbroken chain of cause and effect. In that case, lesser intellects – that is: all of us – would be unable to predict the future in spite of its being predetermined. In other words, thanks to the future’s unpredictability we can calmly continue to believe that it is not predetermined, but we cannot be sure of that. ‘Uncertainty principles’, such as Heisenberg’s, mean that certain things can never be observed, nor therefore measured, nor therefore predicted, but they may well be predetermined. There is no scientific reason for us to conclude that Laplace is right, but not that he is wrong either.

Another question I need to answer here is one I had already anticipated in my book of 2007: why the circuitous approach? Is it really necessary:
– first, to convince readers that Laplace was right and that his definition of determinism is (to quote Hawking) the basis of all modern science;
– next, to reject all brands of compatibilism (including that of Hawking’s ‘effective theory’);
– and finally, to conclude that the only solution is to believe – so to speak ‘against one’s better judgment’ – that there is free will?
Wouldn’t it be more practical to settle for a compatibilist solution, even if it was not entirely satisfactory from a scientific point of view? Tolerating some flexibility in the interpretation of science was surely preferable to introducing faith into a scientific argument.

In my article I had already conceded that it would, of course, be fine if a flexible interpretation of science – from Hume to Hawking – could convince people that there is free will, but added that it would not work for me because I found compatibilist reasoning too smooth to be convincing.

But maybe we should not be too choosy in the selection of our arguments when it comes to refuting Laplacean determinism. I am somewhat daunted by the term ‘existential phenomenology’ because I associate it with metaphysics and I associate metaphysical with unscientific; I have a distaste for compatibilism because I do not trust its scientific credentials; but the solution I prefer is the overtly unscientific belief that there is free will. It may all be the same in the end, but my solution absolves me from the need to prove that the rejection of determinism is rooted in science.

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