Do you think it's ever permissible to cheat?

In a relationship, I think it's sometimes understandable, possibly forgiveable, but not permissible. At school, well, let's be honest. I did for a couple of years on math tests, until I could be bothered to learn my times tables. I'm sure I've accidentally plagarized at least once - I did attempt not too, but it must have happened. However, it drives me crazy when my students do it, so no, I don't think it should be permissible. Tests are about more than just determining how any one child can do, they are also important feedback for teachers as to which lessons have been understood and which haven't. If students cheat, they screw up the chance for a teacher to realise that a concept needs to be retaught.