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Cause and effect offer nothing to fear

12 September 2014

There are robust arguments that can be deployed against atheistic determinists, says Nicholas Turner

CHRISTIANS, and indeed religious people in general, often seem to be frightened of causes. Cause and effect are the very substance of science. Causes, especially, are the instruments of scientists. They seem to show that the decisions that we thought were the result of our own free choice were, in fact, the result of quite other things - genes, environment, chemicals, or even atoms. We imagine that we are free, but in fact our actions are entirely caused by other factors. Where did this strange pessimism come from?

Two hundred years ago this year, one of the world's great science books was first published in Paris, Essai philosophique sur les probabilités by Pierre-Simon Laplace. It is the crucial work for the science of probability, but it is still more influential for just two sentences in its first chapter, which set out a word-picture or thought-experiment that is the foundation of modern determinism.

This popular basis for scientific atheism is still widely believed, and is - most probably - complete nonsense.

Laplace wrote:

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. 

In other words, if we knew everything about the world now and all the laws of nature, then we could know the exact state of the world at any time in the future. Or again, if we knew the exact position of every single particle and the forces acting upon them, then we could know the exact position of any and every particle at any time in the future. This is what is commonly called the Block Universe, where the future is as determined as the past.

Time is treated as a fourth dimension, essentially equivalent to the three dimensions of space. If you imagine moving along the time axis in the same way as along any of the space dimensions, then you can begin to imagine a complete, eternal, static or block universe. Although we ourselves are constrained to one particular time and space, we can, through this picture (it is suggested), see that time and free will are illusions when set against this fixed reality.

WHILE admiring the extraordinary and enduring influence of this simple idea, we should recognise that it is not a scientific theory, for it can in no way be tested; nor is it a proof, for it cannot be demonstrated. It was persuasive initially partly because it expressed the hopes of its age of explaining everything in scientific-mechanical terms, and partly because it was so succinctly expressed by a renowned scientist, second only in reputation to Isaac Newton. It is important to remember, however, that it is just a clever idea, and, I would argue, a wrong one.

The informal philosophical truth on which we base all our science and inquiry, at whatever level - namely that every thing or event has a cause - should not be confused with the notion that everything (i.e. the entire universe) has a cause. It is Laplace's first sentence that is most in err0r. The entire universe is not the cause of its own future. That is a misunderstanding of the term "cause".

THE great thing about causes is that they can make sense only if we exclude information, and do not take into account everything. A good example comes from cricket, in the use of Hawk-Eye technology to decide where the ball would have struck, after an lbw appeal. It gathers the information, adds the laws of motion, and predicts exactly where the ball would have ended up.

In this, it follows the precise procedure that Laplace had in mind. But - and this is the crucial difference - it can do so only by ignoring vast amounts of information, and concentrating only on what is relevant.

The scientific and philosophical understanding of causation is wonderfully complex, but there is always a necessary incompleteness, even vagueness, to the whole idea. What do we mean, for example, by relevance?

If Laplace were right, that a complete analysis of atoms would explain and predict everything, then one of the great modern models of causation (popular among atheists), namely, Darwinian natural selection, would be revealed as every bit as illusory as choice and free will.

If all causation were at the level of physics (Laplace), then there is nothing left for causation at the level of biology (Darwin). 

ALL this is complicated, but it is important that believers should not be browbeaten by earnest determinists. The next time you encounter Laplace's vision of the Block Universe - and if you read any popular science, you cannot fail to do so - remember to say to yourself: "Every thing may have a cause, but not everything."

If a cause cannot make sense, nor be scientifically tested, unless it excludes information, then it cannot also be taken to be something that includes everything.

Think of causes as explanations, and it becomes easier to see that "everything", or even "the exact state of the universe at such-and-such a time", would be worthless answers. They do not explain anything. Nor then (and we are still using picture language) can they constrain, control, or determine anything. Laplace's vision of completeness is only a vision, and an illusory one.

If "everything" is neither the cause nor the effect, this leaves you, me, and everyone else more than enough room not to have our life predetermined, and to allow us to be agents, able to cause things to happen by our own will and decisions. 

The Revd Nicholas Turner is the Rector of Broughton, Marton, and Thornton, in Bradford diocese. Ebook versions of Laplace's works are available free on the internet. For more complicated (and often suspect) refutations of his argument, search for "Laplace's demon", the thought-experiment's popular, but unfair, title.

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