The Standing Invitation

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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to be the most relevant academic treatise on the subject, which I found highly appropriate despite it being 263 years out of date.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.

REFERENCES

Hume’s Enquiry can be found here.

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Written by The S I

September 28, 2011 at 11:59 pm