Learn to science! The value (or otherwise) of personal testimony

According to one of the quotes I just Googled, CSI’s Gil Grissom believes that one piece of physical evidence is worth the testimony of ten eyewitnesses. Now, Grissom may not be the authority on science we’d like to believe he is, but he has a point – personal testimony, however heartfelt, is no substitute for scientific evidence.

Homeopathic medicines, or, more probably, sugar pills (click for source)

I had this concept vaguely in mind when I started looking at the BBC News take on the House of Commons Science and Technology Committee’s recent statement that the use of public money on homeopathic “medicine” was unjustified. It is estimated that about £4 million of the NHS’s budget is spent annually on homeopathic treatments. In their infinite wisdom, the BBC decided to open this topic to the floor, allowing readers to voice their views – a selection of which were published on this page. Helpfully, the BBC chose to divide the comments into two sections: those “against” the public funding of homeopathy, and those “for.”

11 comments have been published on the “against” side of the debate, and 14 “for.” The very first comment on the page, courtesy of a Dr. Gary Grant of Manchester, helpfully sums up what is to come:

Doubtless some of your readers will write in, claiming to have been “cured” by homeopathy, but this isn’t scientific evidence. I might develop a cold the same day I eat macaroni cheese, but this doesn’t prove macaroni cheese causes colds.

In light of Dr. Grant’s comments, I decided to play a little game. I would read through all of the comments on both sides of the debate. Any that used personal experience – “I tried a homeopathic remedy once, and it worked/didn’t work,” – I would disregard.

The result? Seven comments in the “against” section of the page criticised homeopathic spending without resorting to personal testimony. Generally, the criticism was directed at the fact that homeopathy has never been scientifically demonstrated to have more than a placebo effect, and that it lacks the rigorous clinical trials that pharmaceutical medicines have to go through.

Onto the “for” camp. Of these fourteen individuals who claim to support the public funding of homeopathy, how many supported their arguments with claims that it had worked on them, or somebody they know? The answer is thirteen – 13 out of 14 individuals who agree that £4 million of public money should be spent on homeopathy, because they tried it and they believe it worked. Even the one comment I didn’t reject states, “Personally, I have had good experiences with homeopathy.” The reason I didn’t throw that one out as well is because the commenter elaborates no further on his “experiences,” instead reasoning that the NHS should continue to fund homeopathy because “one well patient is better than none.” Whether you agree that £4 million should be spent on treatments of questionable effectiveness, in the hope of curing perhaps a handful of patients every year, is another matter.

Anyway, enough of this cherry-picking. Why, exactly, should we be so careful about using personal testimony in what is – or, at any rate, should be – a scientific discussion? The answer is that – as Grissom might have it – eyewitnesses have a tendency to be flawed. Whether they are flat-out lying or are simply mistaken, evidence from an eyewitness can be inaccurate in many ways. Physical evidence – bullet fragments, insects, whatever – is much harder to fake.

The problem with accepting the testimonies of people who claim to be cured by homeopathic remedies or other “alternative” medicines – and there are thousands of such testimonies – is that, regardless of how loudly they protest, their claims mean nothing if they cannot be scientifically demonstrated. In his comment, Dr. Grant uses the “macaroni” argument as an example of the post hoc, ergo propter hoc fallacy – in English, “after this, therefore because of this.” Proponents of homeopathy tend to base their claims on the fact that they (or someone they know) tried a homeopathic treatment, and afterwards were cured of their ailment. That’s not the same as showing that the treatment was the cure – such a conclusion would require much more rigorous analysis.

As far as I know there are no credible scientific papers that show homeopathic remedies to be any more effective than placebos – and not for want of trying. Without evidence from large-scale studies demonstrating the effectiveness of homeopathy, personal claims are meaningless. People can continue to use homeopathic remedies and shun conventional medicine if it makes them feel good inside – but they should do so at their own expense, with public funding reserved for that which has been demonstrated to a credible degree.

My own view is that a fraction of that £4 million would be better spent informing the public that “alternative” medicines are only so named because they are the alternative to the sort that makes you better.

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2 Comments

Filed under Archive, Politics, Science

2 responses to “Learn to science! The value (or otherwise) of personal testimony

  1. Edward

    So where does that leave me and my four hundred and ninety-two remaining Rohypnol tablets?

  2. Pingback: Of bullies, apologies, slogans, and paranoia | News Time

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