Fibromyalgia syndrome was an attempt to create, for the purposes of investi
gation, a relatively homogeneous clinical entity out of the clinical phenom
ena of musculoskeletal pain and tenderness. The attempt has foundered, aris
ing out of circular argument and violation of its own criteria, thus creati
ng an over-inclusive and ultimately meaningless label. The epistemological
errors include the failure to distinguish a clinical feature from a disease
process, the use of syndromic description without a unifying concept and f
ailure to agree on the importance and biological nature of tenderness itsel
f.