As far as I'm concerned, it's not really a dilemma at all. Your second side is exactly the point: one part of any learning experience must, must be to develop y

As far as I'm concerned, it's not really a dilemma at all. Your second side is exactly the point: one part of any learning experience must, must be to develop your own skills. Learning collaboration is also tremendously valuable, but it can't be the only thing you learn from a class. (And even then, you'd have to be collaborating, not just finding someone else to do the whole job for you.) As a professor, it's good to give your students opportunities to develop in both ways. And for a variety of reasons (some good, some bad), it's more or less necessary to test and grade both types of learning, too. So if a student violates the explicit rules set forth for an exam (which I assume was the case here) by swapping one type of learning for the other, that displays a clear lack of integrity.