What I've been taught is, the part of the sentence after the "but" is the part that's being emphasized. Imagine if you had written: > I've seen shade-tree mec

What I've been taught is, the part of the sentence after the "but" is the part that's being emphasized. Imagine if you had written: > I've seen shade-tree mechanics show a complete disregard for the environment, but I'm not in favor of this kind of law. It seems like you think that's the same sentence as before but to me, and I suspect other readers, they say different things.