> Your definition would include tradesmen and craftworkers, then, who are not strictly professionals. According to what definition? > Anyone can work in wood

> Your definition would include tradesmen and craftworkers, then, who are not strictly professionals. According to what definition? > Anyone can work in wood long enough to say "That wooden bridge looks like it'll hold X people,"... I severely doubt that, given the complexity of trussed bridge designs [0]. There's a lot more to it than how much weight a 4-by-4 can support. > ... and not have any way of conveying how they came to that conclusion... If you can't transfer knowledge in a way that other people can independently verify, you're working in magic. If such a transfer is possible, but simply not possible for a particular person because they lack the tools, then that's a professional failing. For some reason, this state seems acceptable to you when we're talking about physics and complex loads. But could you imagine a doctor describing the appendix as "that thing sticking out where the long thin squiggly bit meets the short thick squiggly bit"? > Also, your definition includes itself as part of its own definition, which is a circular definition fallacy. You can't just throw out "circular definition is fallacy" and dismiss the idea. That itself is a fallacy -- "argument from fallacy". [1] Yes, I use the word "professional" twice, but that's not necessarily a circular definition and especially not necessarily a fallacy. First, the two "professionals" are not the same person. The first mention of "professional" is an individual, while the second mention is a group. What I did is tie membership of a group to a conditional ability which is dependent on the group itself. However, I did cheat a little bit. Because what I did not define is the individual ability necessary to meet that conditional. Because, of course, that changes depending on what group of professionals we are discussing. For backup, let's look at a definition of malpractice [2]: > a dereliction of professional duty or a failure to exercise an ordinary degree of professional skill or learning by one (as a physician) rendering professional services which results in injury, loss, or damage In other words, malpractice is a professional doing something which such a professional should not do... Because the mere fact of a person being a professional implies that they should know better. It's this same logic that I am using: A professional is someone who acts in a professional capacity, and understands the practices of such profession, and thereby is capable of judging whether another person understands and acts in a professional capacity. [0] https://en.wikipedia.org/wiki/Truss_bridge#Truss_types_used_in_bridges https://en.wikipedia.org/wiki/Truss_bridge#Truss_types_used_... [1] https://en.wikipedia.org/wiki/Argument_from_fallacy https://en.wikipedia.org/wiki/Argument_from_fallacy [2] https://www.merriam-webster.com/dictionary/malpractice https://www.merriam-webster.com/dictionary/malpractice