> Well, these "weeder" courses actually make for intellectually lazy education.

I disagree. In order to do well at a subject in an academic setting, you need the upper classmen to be very comfortable with the basics. "Weeder" courses are always (almost always?) in subjects that are basic foundations for the field. The idea is that if you can't pass it, the things that build on it aren't going to make it any easier. As well, they ingrain a good understanding of the content in those who do pass it.

Since schools tailor content difficulty to the ability of the students, lower ability levels of the upper classmen mean that the class difficulty needs to be lowered. If you're in a competitive college that's trying to teach as much as possible, it definitely their call to only filter people with a certain level of ability. Unless you're at a hyper-elite very aggressive school, I doubt that the content is only designed for an ability level that comes only to naturals. It's generally just designed for "people who can do it well". (Obviously, naturals make up a decent portion of it.)

Well you can disagree, but nearly every other subject disagrees with you. They always have two tracks for their subject, one for people who know next to nothing, and one for people who are advanced and might become professionals. In some cases the people from the beginning classes (the 101s) then go on to become professionals.

In addition to that, many other subjects have branches devoted to studying the best way to teach that subject. Computer science is largely missing this, baring some work at universities like CMU and parts of Europe (that I know of).

Until computer science actually starts actively researching how to teach computers science and can produce real research (not their weird non-statistics non-experiments) then these kinds of claims are unfounded. In that event I have to rely on similar research from things like Math and Physics Education which both disagree with you.

Huh, I majored in math, and I can't say that I understand what you mean.

In the lower division (first two years), there is often a separation of core classes between math majors and non-math majors. Calculus, for example, and linear algebra. They served as weeder courses for the math majors so that those who couldn't do good math wouldn't advance onto the upper division courses were they would continue to not do well. In addition, there was a somewhat misc. logic class for math majors that was very strict and served as a choke-point weeder class taken just before you would go onto upper division work.

For non-math majors, the Calculus classes were kind of weeder classes, but that wasn't their purpose. If you were an engineering, the engineers had their own real classes that were their own weeder classes. Etc.

But the two tracks disappeared after lower division. Once you were in 3rd year, there was largely only one set of classes. A couple of them had less rigorous counterparts for those only pursuing a teaching certification, but that was about it.

You are right that CS stands out. It's an unorganized field that is still trying to define itself. (Consider how young it is, relatively speaking.) Some schools want it to be mostly theory, others mostly software engineering, most are somewhere in between. There's disagreement over which languages to teach, how to teach them, etc. It's all somewhat awkward, and it needs to be reformed. I'm hoping that eventually we can split it into two separate fields, like CS theory and software engineering, and do a better job teaching both. (FWIW, I also majored in CS, so I saw both sides of the coin.)