When someone states "I have a Masters in Computer Science" should the word masters have a capital M? I've seen arguments for both and can't determine which is correct.
The word "master's degree", used generically, means the degree attained by a master. For example, using it in this sentence is correct:
I received my master's degree from the university last January.
The capitalised form is usually used to refer to a specific master's degree by name:
I received my Master['s] of Science degree from the University of Waterloo last January.
Universities may use any of "Master", "Master's" or "Masters" when naming their specific master's degree, and you should use the same one.
I do not agree with the specific name example. The 'D' in "Master of Science Degree" needs to be capitalized for it to be a name, and capitalization in this syntax is optional but not recommended. Only proper names need to be capitalized. Titles on the other hand are always capitalized, so the title "University of Waterloo Master of Science Degree" gets capitalized throughout. It's a finicky rule but so are many other rules of English grammar.