There has been a lot of debate regarding the "Profession of Arms". Is the American Soldier a Professional, or something else entirely?

CPT (Join to see), you left a key word undefined; "profession." Without ascertaining that definition, the meaning of "professional" is vague at best.

Keeping with your use of Webster: http://www.merriam-webster.com/dictionary/profession.
a : a calling requiring specialized knowledge and often long and intensive academic preparation
b : a principal calling, vocation, or employment
c : the whole body of persons engaged in a calling

I don't believe Webster's definition is good enough for us. If being a professional means conforming to the "technical or ethical standards of a profession," but a "profession" requires only "specialized knowledge and *often* [i.e. not necessarily] long and intensive academic preparation," then there may be no technical or ethical standards to which one can aspire.

I think a profession is *characterized by its ethics.* That is, we must have an ethic, or a values system, or a code by which to conduct ourselves. Therefore, being a professional means belonging to an institution guided by a code of principles to which the particular individual aspires and commits him/herself.

Rank is immaterial to being a professional. I love Sgt Aaron Kennedy, MS's analogy to the apprenticeship system. Whatever we call it does not really matter.

In a sense we are all professional Soldiers, Sailors, Airmen or Coast Guardsmen. We are trained and have excelled at what we do.

A professional is one who is trained in a profession and conforms to its standards, working ever forward. Using the old system. There are Apprentices, Journeymen, and Masters.

That said, it doesn't really take a certain rank to become a "Professional Soldier" however it might be more appropriate to say someone is an Apprentice level Soldier at X Rank, Journeyman at Y Rank, and Master at Z Rank.