Hunting, immigration, animal testing, dyslexia: some issues are guaranteed to evoke emotional reactions. As I stood in the grounds of Durham University a few months ago, berated by some who had just attended my lecture questioning the scientific status of dyslexia, all the time my discomfort being filmed by a Channel 4 television crew, I recognised that an appeal to logic or science was insufficient. Dyslexia persists as a construct largely because it serves an emotional, not a scientific, function.
Let's be absolutely clear about the concept of dyslexia from the outset.
First, there is no consensus about how it should be defined or what diagnostic criteria should be used. Forget about letter reversals, clumsiness, inconsistent hand preference and poor memory - these are commonly found in people without reading difficulties, and in poor readers not considered to be dyslexic.
After three decades as an educationist - first as a teacher of children with learning difficulties, then as an educational psychologist and, latterly, as an academic who has reviewed the dyslexia literature - I have little confidence in my (or others') ability to offer a diagnosis of dyslexia.
What I can explore includes an individual's strengths and weaknesses in reading and spelling, which strategies they typically employ, any visual or phonological problems that are experienced, whether working memory is problematic and the extent to which anxiety or learnt helplessness affect performance.
I can offer an assessment of an individual's circumstances and offer guidance for intervention, but attempting to allocate a person to one of two groups - dyslexic sheep or ordinary poor reading goats - is an endeavour I would wish to avoid. Advances in genetics and brain studies may one day help us to make meaningful distinctions, but we are still a long way away.
There is, however, an equally damning failing of the dyslexia "industry" - that is, the spurious link between diagnosis and intervention. In medicine, a diagnosis is typically undertaken in the belief that this will indicate the most appropriate form of treatment. Similarly, many believe that a diagnosis of dyslexia will signpost appropriate intervention and, ultimately, a clear path to "recovery".
One frequently hears: "I was not diagnosed dyslexic until the age of 'x'.
If only this had happened earlier, my problems could have been prevented."
Yet a diagnosis of dyslexia tells us virtually nothing about how best the individual can be helped to become a better reader.
Contrary to claims of miracle cures, there is no sound, widely accepted, body of scientific work that has shown that there exists any particular teaching approach which is more appropriate for "dyslexic" children than for other poor readers.
There are, as was suggested on a Channel 4 programme last week, approaches which have great promise. Yet these appear to help all youngsters, not merely a subgroup of so-called dyslexics.
Let's not beat about the bush, though; let's get the key issue out into the open. Behind all the rhetoric and reasoning, the anger and the angst, lies the thorny question of intellect and its relationship to literacy.
Anxieties abound in this area, embodied in the words of the mother of a child I was assessing: "Our Darren can't read very well but he's not stupid. Not like his father - he went to the daft school."
Public perceptions often link reading difficulties with intelligence and, in our culture, an attribution of low intelligence often results in feelings of shame and humiliation.
It is hardly surprising, therefore, that the widespread, yet wholly erroneous, belief that dyslexics are intellectually bright but poor readers would create a strong, sometimes impassioned demand to be accorded a dyslexic label. The fact that decoding text is, in reality, a low-level cognitive activity that can sometimes be accomplished by those with severe intellectual difficulties often passes unnoticed.
Yes, of course teachers should not make assumptions about a child's cognitive ability primarily based upon existing levels of literacy. Yes, of course we need to provide detailed assessments. Yes, of course some children will require special resources and dispensations, but we certainly don't need spurious diagnoses of dyslexia to achieve such ends.
Julian Elliott is professor of education at Durham University. A follow-up conference to The Dyslexia Myth (broadcast on Channel 4 on September 8) will be held in London on October 21. For details, e-mail: Kalvinder.Dhillon@ cem.dur.ac.uk.