To defend the concept of plausible reasoning as involving "thinking that is analogical and associative rather than logico-deductive" (Letters, May 6) is simply not good enough in the context of examinations that judge people according to whether they have given the "right" or "wrong" response to a question.
Classification on this basis confines the imagination to a straitjacket of second-guessing and discriminates against those people whose intuition tells them to be logical.
No doubt there is something abnormal about associating a picture of a cone backed by amorphous shaded objects with the drawings of Philip Guston and finding the relationship between this image and the set of propositions given no more plausible nor implausible than the statement "the chance meeting on an ironing-board of a sewing-machine and an orange umbrella".
Conjecture by plausible reasoning in mathematics is very different from ascribing plausibility to the potentially radically disjunct face-off between word and figure.
Anthony Mellors
University of Central England