In the latest Diagnostic and Statistics Manual (DSM-5-TR), intellectual disability is the term that replaces mental retardation meaning mentally slow or delayed. Before mental retardation, it was mental deficiency implying there was something inferior. To me, there's no real difference between mental deficiency and intellectual disability. They are synonymous. Before the first DSM, a prominent doctor in the field of intelligence created a tiered system of intelligence that applied the labels moron, imbecile, and idiot (ordered higher to lower intelligence). Those words became derogatory too. The issue is not that scientists can't guess the correct term that wont become an insult.
The issue is that society defines values for people which allows terms to be insults. As long as oppression exists, the vulnerable will fall victim to it. The disabled, by definition, will always be part of the vulnerable group. Additionally, oppression is always justified by arguments on who deserves what, whether it be religion, race, sex, social class, work ethic, or intelligence. As long as we hold the value that inequitable distribution is not only acceptable but the ultimate goal of a just society, then regardless of the rules we establish, however noble or virtuous, the disabled will always be part of the oppressed, and thus, the terms for lower intelligence will continually evolve from neutral to derogatory.
Should you put glue in pizza?
by Perplexity