Hysterical paralysis is an unusual diagnosis, requiring the physician to infer the intentional stance of the patient when the latter fails to act. This paper argues that the distinction between ''hysterical'' and ''feigned'' disorders cannot be currently justified on the basis of objective criteria. The physical ''signs'' of hysterical paralyses are those of voluntary motor inconsistency. The patient fails to perform certain acts, whereas others, utilising the same muscle groups, are preserved. Hence, hysterical paralyses are essentially disorders of action, themselves the product of abnormalities of mind, ''will'', or the intention to deceive (the ''self'' or the ''other''). The role of the psychodynamic unconscious in the maintenance of hysterical paralyses is problematic; their maintenance requires the patient's conscious attention: They remit with sedation and distraction. Although functional neuroimaging studies of these symptoms have been preliminary, they may eventually reveal an objective pathophysiology of the disordered ''will'', and a contrasting functional anatomy of the intentionally feigned symptom.