In their 1928 book The Child in America: Behavior Problems and Programs, William Isaac Thomas and Dorothy Swaine Thomas proclaimed one of sociology's most influential ideas: "If men define situations as being real, then they are real in their consequences." Their case in point was a prisoner who had attacked people he had heard mumbling absent-mindedly to themselves. The deranged prisoner had imagined their lip movements to be curses or insults which were directed at him. It did not matter that they weren't; the results were the same.

The 'Thomas Theorem' has a corollary in how we perceive language. If we perceive it as being insulting or negative in connotation, then the practical consequence will be that it is insulting, regardless of whether either the denotation of the language or the intent with which it was delivered had been. This may be seen via references to "canola" rather than "rapeseed" oil, or the differing pronunciation of words such as "harassment" and "Uranus."

Two other examples are the 1999 Washington 'niggardly' incident and the Northern Illinois University anthropology class reported by Mike Salovesh involving a citation of 'nigger'.