The British Dyslexia Association (BDA 1989) defines thus:

Dyslexia can be defined as a specific difficulty in learning, constitutional in origin, in one or more areas of reading, spelling and written language which may be accompanied by difficulty in number work. It is particularly related to mastering and using written language (alphabetic, numerical & musical notation) although often affecting oral language to some degree.

This is precise, in that it specifies that the syndrome is related to written symbols which represent language (or music and possibly number) and that it is definitely constitutional in origin. As we will see, this simple assertion (that there is such a specific difficulty) remains doubtful.

Moray House (1993) defines thus:

Specific learning difficulties can be identified as distinctive patterns of difficulties, relating to the processing of information, within a continuum from very mild to extremely severe, which result in restrictions in literacy development and discrepancies in performances within the curriculum. Reid (1994 p. 3)

This definition very properly, as with the one above, restricts its scope to literacy, which is more than many do. (dys [Greek] means difficult, abnormal, impaired and lexikos [also Greek] means pertaining to words. Let us not forget this.) It relates the difficulties, though, to defective information processing. This sounds satisfyingly scientific and would, perhaps, be a satisfactory explanation for a defective computer. However, in today’s climate of deep ignorance as to what, exactly, our brains consider ‘information’ to be, what they actually use as ‘information’, and just exactly what they are doing when they ‘process’ it, the phrase ‘information processing’ denotes too vague and ill-understood a concept to be of much psychological value, at least as yet. We are certainly not in any position to assess it in any very meaningful way, particularly not in a neurologically meaningful way. (and see Chalmers 1996, Reilly 1985 & Smith in Olson et al 1985) This definition amounts to declaring that specific learning difficulties are difficulties in learning which vary from very mild to very severe, and that these difficulties are related to a deficit in a process of which we have extremely small understanding. The patterns of difficulty are allegedly ‘distinctive’, but in an unspecified way.

I will be discussing the use of the diagnosis as an alibi explanation, and as one which very conveniently, and comfortingly, locates the blame for literacy failure entirely within the victim’s central nervous system. Occasionally even the internationally recognised expert lets this one out of the bag as in Miles (1988) quoted in Pumfrey & Reason (1991 p. 69):

For him [Miles] the term dyslexia assists parents and the child to make sense of occurrences they know to exist. They know the child has difficulty with reading and spelling; they need explanations which remove the sense of self-blame.

Pumfrey and Reason compare this with the ‘it’s my hormones’ explanation of obesity. It is comforting, perhaps, as it absolves from responsibility, but this explanation entirely fails to understand, or make any attempt to solve, the real problem which, as we all strongly suspect, has nothing to do with hormones. An elephant in the room, in fact.

And then sometimes researchers let another out of the bag as when Cooke says (2001 p. 49):

Miles (1995) has questioned whether there can be a single definition of dyslexia; she suggests instead that different people, and different groups, will want a definition to suit their own requirements. This is clearly correct…