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Posts Tagged ‘Scepticism

Hume on Neutrinos

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With the scientific world abuzz with reports of neutrinos appearing to travel faster than the speed of light, I have become painfully aware that what I know about modern physics I could fold in half and fit between the keys of a typewriter without seriously impeding its function.

So when I heard about the discovery, I went to what I felt to be the most relevant academic treatise on the subject, which I found highly appropriate despite it being 263 years out of date.

David Hume’s Enquiry Concerning Human Understanding was published in 1748 and deals with the problem of how we are able to know things. Since Hume believed that everything we know comes from experience ­– from evidence and experimentation, as opposed to revelation and belief – the book hits at the very core of scientific way of thinking.

When I heard of a discovery that appears to completely contradict the present scientific consensus, I went to Hume. In particular I went to chapter 10 of his Enquiry, a two-part essay entitled Of Miracles.

A miracle, for Hume, is “a violation of the laws of nature”. We determine the laws of nature by our experiences of how the world works. What we call a ‘good’ law of nature is one that we see demonstrated over and over again. Every time we have let go of a ball in mid-air, it has fallen; through habit of association we come to expect that the ball will always fall, and we arrive at a law of nature that says that all released balls fall ­– let’s call this gravity.

The questions is: how should we react to someone’s story that once he saw a ball float in mid-air ­– that he saw the force of gravity disappear? In essence, how should we react to a miracle?

Hume’s general principle, and it’s a good one, is this: “That no testimony is sufficient to establish a miracle, unless the testimony be of such a kind, that its falsehood would be more miraculous, than the fact, which it endeavours to establish.”

In the case of our friend saying the ball didn’t fall, we must ask ourselves: what is more likely? That the man is mistaken/lying/joking, or that gravity really did stop for him? If it’s just one man’s account, unsupported by evidence, then of course we are within our rights to dismiss him out of hand (A more modern commentator: “What can be asserted without evidence can also be dismissed without evidence.”)

But if he comes back with photos, confirmatory experiments, and other, independent witnesses, eventually it comes to the point where it really would be more miraculous that this was a mistake. Then gravity would be a weakened hypothesis. We would pose a new law of nature: that gravity usually holds, but in some cases doesn’t, as in the following examples…

Whatever new theory, or extension of the old one, takes the place of the traditional concept of gravity, we would listen to it, but with caution and scepticism, until the evidence in its favour built up to make it more certain.

Whenever a scientist ­– or indeed anyone at all – comes out with something new, something really new, think of sceptical old Hume. In his own words:

A wise man … proceeds with more caution: he weighs the opposite experiments: he considers which side is supported by the greater number of experiments: to that side he inclines, with doubt and hesitation; and when at last he fixes his judgement, the evidence exceeds not what we properly call probability.


Hume’s Enquiry can be found here.

Written by The S I

September 28, 2011 at 11:59 pm

When Not To Let The Skies Fall

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The search for scientific knowledge is a glorious and essential enterprise. But is it always? Are there some topics for scientific enquiry that are morally wrong to pursue? Are there situations where it might be irresponsible or harmful even to ask a question?

This breaks down into two questions:

1) Are there some experiments the carrying out of which is harmful, even if it gives us the truth?

2) Are there some experiments the outcome of which is harmful, even if it gives us the truth?

The first question is so easy it’s uninteresting. Of course there are limits to how far a scientist can justifiably go in the pursuit of knowledge – just like there are limits to what a businessman can do in the pursuit of money, or a policeman in the pursuit of criminals. A scientist might want to know how long a virus takes to kill a child; but to deliberately infect the child and stand there with a stopwatch would be totally unacceptable. Being a scientist does not excuse you from social responsibilities and obligations.

So question 1 is easy. But what about question 2? Are there questions we should not answer, because it is better to be ignorant than know the truth?

One might be tempted to quote the phrase from antiquity, “Do justice and let the skies fall.” But this is a cop-out. Sometimes knowing the truth about something is actually measurably harmful. There might be good medical reasons for giving a patient a placebo for pain management; informing the patient that it is a placebo might inflict harm on the patient.

This is perhaps a special case. Nevertheless, a scientist must be aware of the consequences of his actions, even if the only action is inquiry. In a society in which racism is prevalent, investigation into correlations between race and intelligence might be used as ammunition for white supremacists. Investigation into the potency of a new strain of virus might cause a panic that harms more people than the knowledge saves.

Ultimately, the truth is worth knowing precisely because it is true. It is a deeply flawed society that can’t handle some unpleasant truths, or that misinterprets truths so badly that people get hurt for no logical reason; and yet that is the society in which we live, unjust, dangerous and full of misconceptions. To proceed blindly in any activity ­– scientific or not – without acknowledging this fact is deeply irresponsible.

Much is made of the need to educate the public about science, and I can’t agree more. Life is made so much richer by understanding, and knowledge is good for the soul. But I feel that what is needed today is not to teach people facts, but to teach people method – not what scientists know, but how they think. Facts about race or risk are less dangerous to a public that understands statistics, that knows what a randomised controlled trial is. There is no better armour for harsh truths.

Written by The S I

September 2, 2011 at 11:59 pm