Amateurs vs Professionals

In today's class we discussed the difference between amateurs and professionals. In a sense I would say that most of us in the class had some of the same views on the subject. Personally I believe that professionals or amateurs do not have to be defined by a certain amount of credentials but mainly by the quality of the work. However, I say that based upon what the field might be. For a photographer for example, you don't have to have a degree in photography to have professional work but the quality of the work is how your audience will deem it professional or not. The same may not go for teachers. I would think that you would want to feel confident in the person who is considered the professional and that you will learn the most amount of info or gain the highest quality work. Society gives the title to who is seen as an amateur as opposed to a professional. Unless you strictly participate in a hobby for yourself and have no desire to be a professional everyone is more than likely trying to become a professional at something. That is one of the main reasons of school. To gain a degree and become a professional in your career and to be recognized as such. At least that is a goal of mine but I also do some amateur work on the side in certain fields. So am I only aiming to be a amateur in certain things? I don't really know that there is one way to clearly differentiate the two but I also wonder what is the actual importance of classifying one over the other? What does anyone else think?

I make some of those comments solely based on a certain career field. Anything dealing with medicine I would assume most of us would only want a certified and professional doctor working with us.