I'll try to answer the question to the extent that I understand the topic, which isn't great given that my son is only a freshman. But double majors were a topic of interest for him and based on what he and I have read on Pitt's website I think that:
Double or triple majors
- can be majors in any discipline, regardless of how much or how little they overlap; obviously, the more they overlap, the easier it is to complete the combined requirements
- I don't remember reading about a general limit (i.e. one that applies to the entire A&S) on how many courses may overlap, so I'm assuming that there is none, but you would be well advised to read about the degree requirements for each of your intended majors to verify that there aren't any department or major-specific restrictions
- I believe this is what schrizto was referring to when talking about disciplines that overlap to some extent--or that simply make sense together
- some departments, such as Mathematics, Philosophy, etc. do indeed offer them. They are described as multidisciplinary majors offered by two or more departments and they are designed in such a way as to eliminate or minimize redundancies. Therefore, they are typically considered to be a simpler alternative for students who would otherwise double or triple major in those areas. Some departments, such as Philosophy, even allow you to work with an advisor to design your own joint major.
Hope this helps.