Why does Mr Spock address Doctor McCoy as 'Sir' in 'The Trouble with Tribbles'? I thought Mr Spock was the doctor's senior officer?

  • 1
    I think, given the tone of that scene, it could have been meant sarcastically. That, or it was a writers error. Spock is a Commander, and Bones is a Lt. Commander.
    – PiousVenom
    Apr 23, 2015 at 16:01
  • 1
    @MyCodeSucks When is Spock ever sarcastic? Apr 23, 2015 at 16:05
  • 1
    There's been moment's he lets his human side through, even accidentally.
    – PiousVenom
    Apr 23, 2015 at 16:06
  • What was McCoy's official rank, anyway? I don't recall it ever being mentioned in the original series. Given his age and postion as senior medical officer, I always assumed he was a Commander or equivalent, roughly the same rank as Spock.
    – Joe L.
    Apr 23, 2015 at 16:38
  • 2
    @JoeL.: Why does it need to be mentioned? That's why everyone wears rank insignia. Apr 23, 2015 at 16:52

2 Answers 2


Why does Mr Spock address Doctor McCoy as 'Sir' in 'The Trouble with Tribbles'? I thought Mr Spock was the doctor's senior officer?

I believe in one episode ("Arena"?) Spock tells McCoy "You, sir, are a hedonist." and McCoy says yes he is. In that episode Spock was not calling McCoy "sir" as a sign of personal respect for McCoy nor in reference to McCoy's nonexistent superior rank, but as an example of Spock's formal way of speaking, as in, for example, telling someone "you, sir, are a cad."

If you tell someone "you, sir, are a cad." the "sir" is not meant as respect for the person but as a formal and polite mode of addressing someone you are insulting.


According to this site, it looks like doctors (medical personnel) fit differently in RL military hierarchy.

There are also two basic "types" of commissioned officers: Line and Non-Line. A Non-line officer is a non-combat specialist which includes medical officers (doctors and nurses), lawyers, and chaplains. Non-Line officers cannot command combat troops. For example, let's assume there was an infantry unit in combat, commanded by an infantry lieutenant. A captain, who is a Military Chaplain is attached to the unit. The Captain cannot issue any commands relating to the combat operation to the lieutenant or anyone else in the unit. If the lieutenant dies, command shifts to the highest ranking warrant officer or enlisted member, not to the chaplain captain.

As a "line officer", Spock effectively outranks McCoy, even if McCoy held the same or higher command rank than Spock. Spock's use of "sir" when referring to Dr. McCoy is most likely a gesture of respect for McCoy's medical degree, as well as for McCoy himself, rather than anything to do with arbitrary rules about rank.

  • 5
    For the purposes of military courtesy, line officers do not outrank staff officers who they don't actually have a higher rank than. A staff officer is limited in terms of who they can command, but they are still entitled to the full courtesy due someone of their rank; a line officer is expected to call a staff officer "sir" if the staff officer outranks them.
    – cpast
    Apr 29, 2015 at 7:59

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.