Testimonial

An appeal involving someone's unsupported opinion in favour of a conclusion, belief, hypothesis, etc. – in cases in which the claim’s sole support comes from testimonials there is a greater likelihood the claim is of lower credibility, dubious, problematic, etc. In essence: someone’s recommendation that something is true, acceptable, or worthy of one’s time, money, assistance, etc., or that something should be done, e.g., some course-of-action taken – a particular kind of personal experience. (cf. expert testimony)

In many contexts, testimonials count as poor quality evidence – what has been referred to as “a biased sample of one”. What is the expertise of the ‘testimonialist’ in reference to the claim they are exhorting? How might their interests, values, and biases affect the credibility of their testimonial? Consider the case in which a government department or body sets up an independent expert panel to study the effects of a drug to decide whether the drug is unsafe. After investigations the panel issues it report and subsequently the chairperson of the panel appears on a leading news analysis television programme to explore and explain the panel’s findings – during which the chairperson makes a number of statements about the safety of the drug in question – this expert’s recommendations differ considerably in quality from most testimonials encountered. (strictly speaking, if the chairperson adheres closely to the expert findings in the panel's report their's is not a testimonial in the sense given above)

Testimonials have some similarity to case studies, in that they are isolated events. The problem of relying upon testimonial evidence is that since testimonials can be found (or simply ‘show-up’) to provide support for virtually any proposed conclusion or claim, how much value should be placed on them in assessing the veracity of a claim in any specific case? For example, subliminal self-help audio-tapes are marketed with the assertion that listening to the imbedded messages under the breaking waves (or some other overlayed, usually, ‘soothing’ sounds) raises memory performance or self esteem and generates no small number of testimonials, yet controlled studies show that such tapes have no affect on memory or self-esteem.

The information is likely to be highly selective in favour of the claim – or if from an opponent, against the claim – since people who wish to convince us of something seldom, if ever, offer us a testimonial against what they are arguing for and supporting. What are the experiences of those people who have used a particular product being marketed, but are not featured in an advertisement paid for by those wishing to sell it to us? Often we will have too little information (and not of an adequate kind) to provide a good basis for the judgement asked of us. Such expressions of positive evaluation offered by people who can seem so trustworthy, well-meaning, and honest, and, unlike ‘dry’ statistics, are characterized by enthusiasm, vividness, and fascinating detail, have a particular compelling nature such that many information consumers will want to believe their story.

Like personal experience in general, testimonials provide no reasonable basis for ruling out alternative explanations – they lack the comparative information necessary to demonstrate that one claim or hypothesis is superior to its viable, competing alternatives. It is misleading and irresponsible to advance testimonial evidence – as is usually the case with pseudo-scientists and ‘advertorial types’ and their ‘pitches’ to the general public – without emphasizing that such evidence is open to a wide range of alternative explanations.

This problem is underlined by the example of the placebo effect, and response expectancies more generally: it has been clearly established that the mere suggestion that a treatment being administered to subjects or patients is effective is enough to make many people feel better. When a new drug is being tested on patients an equivalent group is formed and given an inert pill – one which does not contain the pharmaceutical being tested – usually made to look identical to the active treatment, to control for people’s tendency to feel better when any new treatment is introduced.

Imagine a person who already ardently believes in the power of ‘faith healing’ and who then attends a faith healing service for some ailment. Should we subsequently have contact with them the chances are that they will regale us with their startling ‘laying-on-of-hands’ experience and miraculous ‘cure’, but how much factual value would one place upon their ‘witness’?

Unwarranted reliance upon testimonials and case studies can result in distinctly adverse consequences such as the misconception, and perpetuation of unfalsifiable, and false, psychoanalytic explanations about Tourette’s syndrome, when the condition is in fact organically-based. The use of persuasive testimonials has been perpetrated by undesirables to lure people with serious, life-threatening illnesses to travel to far-flung, exotic locations for extravagantly-expensive, but useless treatments at the expense of those unfortunate souls receiving effective, evidence-based care, regrettably sometimes resulting in deaths or serious complications.