Writing to Peter Singer about Down syndrome

I liked this Michael Bérubé post; here is an excerpt:

…in the 1920s we were told that people with Down syndrome were incapable of learning to speak; in the 1970s, we were told that people with Down syndrome were incapable of learning how to read.  OK, so now the rationale for seeing these people as somewhat less than human is their likely comprehension of Woody Allen films.  Twenty years from now we’ll be hearing “sure, they get Woody Allen, but only his early comedies–they completely fail to appreciate the breakthrough of Interiors.”  Surely you understand my sense that the goalposts are being moved around here in a rather arbitrary fashion…

You’re looking for things people with Down syndrome can’t do, and I’m looking for things they can.  We each have our reasons, of course.  But I don’t accept the premise that cognitive capacity is a useful criterion for reading some people out of the human community, any more than you would accept the premise that we should grant rights to animals on the basis of whether humans think they do or don’t taste good with barbeque sauce.