As others have said, what is adequate will depend on the program.
I just got myself a new laptop for back to school, and honestly I went cheap with it. I don't need to run anything more demanding than Office or InDesign, and the vast majority of what I use it for is word processing and internet research. And while I did like the MacBook I looked at I just couldn't justify the extra cost over what the Lenovo Yoga I ended up getting cost. I have to say, I love the convenience of the convertible design too. It is really nice to be able to put it into tablet mode when I'm doing something where drawing or marking up with a stylus is easier than working with a keyboard and mouse/touchpad.
The main thing I'd keep in mind, outside of major-specific software demands, is portability. I was using DD's 15" Lenovo last year and that thing was a bit annoying to lug around... Not a good fit in my backpack and as heavy as some of my textbooks. Now that she's played around with my 11" a bit she's wanting a smaller one too because she's taking hers to school every day for an online class!
ETA: The school I attend does have computer labs but I wouldn't want to count on them. I'm sure there's plenty of availability in the evenings and on weekends, but as a commuter school the labs are crazy busy and it can be hard to find an open machine during the day. That's why I started carrying my daughter's computer in the first place, because I had an hour and a half between two classes and got sick of not being able to get anything done for lack of a free computer in the lab or library at that time of day.