In psychiatry, dysaesthesia aethiopica was an alleged mental illness described by American physician Samuel A. Cartwright in 1851, which proposed a theory for the cause of laziness among slaves. Today, dysaesthesia aethiopica is considered an example of pseudoscience, and part of the edifice of scientific racism.
Found exclusively among Blacks, dysaesthesia aethiopica - "called by overseers 'rascality'" - was characterized by partial insensitivity of the skin and "so great a hebetude of the intellectual faculties, as to be like a person half asleep." Other symptoms included "lesions of the body discoverable to the medical observer, which are always present and sufficient to account for the symptoms." Cartwright noted that the existence of dysaesthesia aethiopica was "clearly established by the most direct and positive testimony," but other doctors had failed to notice it because their "attention [had] not been sufficiently directed to the maladies of the negro race."
According to Cartwright, dysaesthesia aethiopica was "much more prevalent among free negroes living in clusters by themselves, than among slaves on our plantations, and attacks only such slaves as live like free negroes in regard to diet, drinks, exercise, etc." - indeed, according to Cartwright, "nearly all [free negroes] are more or less afflicted with it, that have not got some white person to direct and to take care of them." He explicitly dismissed the opinion which assigned the causes of the "problematic" behaviour to the social situation of the slaves without further justifications: "[The northern physicians] ignorantly attribute the symptoms to the debasing influence of slavery on the mind."
Cartwright felt that dysaesthesia aethiopica was "easily curable, if treated on sound physiological principles." Insensitivity of the skin was one symptom of the disease, so the skin should be stimulated:
The best means to stimulate the skin is, first, to have the patient well washed with warm water and soap; then, to anoint it all over in oil, and to slap the oil in with a broad leather strap; then to put the patient to some hard kind of work in the sunshine.
Author Vanessa Jackson has noted that lesions were a symptom of dysaesthesia aethiopica and "the ever-resourceful Dr. Cartwright determined that whipping could ... cure this disorder. Of course, one wonders if the whipping were not the cause of the 'lesions' that confirmed the diagnosis."
According to Cartwright, after the prescribed "course of treatment" the slave will "look grateful and thankful to the white man whose compulsory power ... has restored his sensation and dispelled the mist that clouded his intellect."