> how do you prove his credentials? You don't. "Engineer" is not broadly considered a claim of authority. It is a claim of knowledge. If I am required to pro

> how do you prove his credentials? You don't. "Engineer" is not broadly considered a claim of authority. It is a claim of knowledge. If I am required to provide credentials whenever I say "engineer", then how, as someone without credentials, am I supposed to express my background? I'll simply choose another word, which will have the exact meaning that "engineer" currently does. Why? Because you redefined the word. The word "engineer" is perfectly adequate in its current state. If you really want to know whether you can trust an engineer in his or her capacity, you will then ask for some credentials, like a degree or state-sponsored license. The fact that anyone can use the word "engineer" to describe him or herself does not in any way detract from that. The reason that MD, EMT, or police officer are different is that every individual who claims that title is treated with authority.