If all (e.g.) 7th graders must have the same knowledge of math, that knowledge of math cannot exceed the knowledge attainable by the dumbest (read: any) 7th grader. This is tautologically true.
Yes, thanks. That clears it up. You're right. We must teach no one anything otherwise there would be some people that wouldn't be able to understand. That was exactly what I was thinking and your example helped me understand. What you were saying was clearly tautological and I just didn't have the logical training to understand it.
Your interpretation of what I was saying was clearly adversarial and uncharitable so I just got tired of it. It's entirely possible to have high standards for everyone (including the "stupid") without reducing the quality of the curriculum. But you're not interested in having that discussion because you're grinding some other axe about what you perceive to be the ideological takeover of the educational system.