Is or Was when talking about a historic figure in the present?

Solution 1:

If you do not know that Martin Luther King Jr. is deceased, you can ask "Who is Martin Luther King Jr.?"

If you have figured out that he is dead, and you want to know more about Martin Luther King Jr. as a person, you can ask "Who was Martin Luther King Jr.?" This can get you the facts about his life and possibly a lot of information on his legacy (hearer's choice).

If you want to refer to his person (the man) as a symbol of "what that he means", you can say "Who is Martin Luther King Jr.?" or "Who is Martin Luther King Jr. today" or "Who is Martin Luther King Jr. for us?" or...

Solution 2:

They are both correct.

In legal writing, we regularly discuss past issues--sometimes discussing events in cases from hundreds of years ago. There are two things that matter: subject-verb agreement within the sentence, and consistent "voice" within the document.

In your example, in colloquial speech, both forms are acceptable. If you are giving an oral presentation or writing a document, use either form as long as it matches the tense ("voice") of your other sentences.

Caveat: there are situations when you will want to break this rule. For example, you might tell a story about John Doe and you might have John Doe speak about MLK in a different tense ("voice") than you are using in the rest of the document. This is acceptable and sometimes useful.

Solution 3:

I am grammatically untutored, so my response is directed only at the propriety of asking who a deceased person--in this case, one of great public acclaim--is, rather than asking who that person, was. I would answer that, though Martin Luther King Jr. is deceased his legacy lives and endures. In the case of a personage such as Dr. King, I don't believe that you can productively separate this man from his legacy, so I feel it would be completely acceptable--that is, not improper--to ask, "Who is Dr. Martin Luther King Jr.?" Grammarians may respond differently.