Like some who would argue about sexual gender and orientation, "Dumb" in the certain communities I worked with before retiring, means "Mute, unable to verbally speak." It does not mean that they are stupid or lack intelligence, as a lot of handicapped people I worked with are more intelligent than the normal general population. They just communicate on a totally different manner than everyone else.
Define "Dumb." Like some who would argue about sexual gender and orientation, "Dumb" in the certain
