Borne from racism
The names and mascots are borne from a place of racism, not respect.
Seeing their culture portrayed in team mascots, as bumbling clumsy entertainers with red faces and wide smiles is damaging to the self-esteem of young Native Americans.
Seeing oneself and one’s ethnic group portrayed in this way fosters a negative view of oneself and one’s community. It also shows society at large that it is socially acceptable to perceive Native Americans in a negative way. This can have far-reaching consequences for the next generation of Native Americans, who will not only have to deal with deep-rooted, harmful stereotypes but will be confronted by a society that deems is perfectly acceptable to harbour negative views of their race. In 2005, the American Psychological Association (APA) called for the ban of Native American mascots, images and personalities in professional and amateur sports. One of their key sticking points was that it harmed young Native people’s self-esteem and social identity. Stephanie Fryberg carried out a study on the way depictions of Native American people in popular culture impact Native American teens. She found that after being subject to images of Chief Wahoo (the Cleveland Indians' mascot) and Chief Illiniwek (mascot for the University of Illinois), Native American teens registered lower ratings of self-esteem.  The next generation of Native Americans needs our support, not our mockery. They already have to grapple with issues of social identity and contend with negative stereotypes about their culture and behaviour. Within this context, sports teams using Native American mascots become highly offensive and damaging.
Enter the counter arguments here ...
[P1] Seeing one's culture portrayed as a mascot damages one's self-esteem. [P2] Therefore, the use of Native American imagery and symbolism in sports is offensive.
Enter the technical rejections of the premises here ...