I could never understand exactly what Zachary Smith was a doctor of. We know he isn't dumb; it takes genius to make up things like, "You bubble-headed BOOBY!!"
For who would bear the whips and scorns of Hollywood... (;-p)
When the series began, he was a Medical Doctor. He gave the family their final pre lift-off physical checks in the first episode. In the 3rd season (Kidnapped In Space), he said he was a "Full fledged Doctor of Intergalactic Environmental Psychology".
In episode 9, "The Oasis," when Judy is speculating that she might have eaten the alien fruit, just as Smith did, John says, "No, Judy, you wouldn't have touched it. Now, you've had plenty of training in interplanetary travel, like the rest of us. As for Smith, he's a doctor - and he's had much more experience than you have."
Clearly, John is suggesting that Smith should have known better because he was a medical doctor, not because he was a PhD - although I suppose that Smith might have been a psychiatrist. Psychiatrists are MD's.
As the show progressed, I think they decided that the Smith character was incompatible with any serious medical field, so they just made him a sort of quack in the invented field of Intergalactic Environmental Psychology.
At the time, they seemed to think that "Environmental" sounded scientific. The robot was officially an "Environmental Control Robot," presumably because it tested alien environments for compatibility with human life. What it "controlled," I don't know.
<<<I think they decided that the Smith character was incompatible with any serious medical field, so they just made him a sort of quack in the invented field of Intergalactic Environmental Psychology.
iirc, even the Robot called him a quack. (several times).
Sometimes I feel like Smith may have been just a plant, a spy given false credentials and so perhaps wasn't a Colonel (or a doctor)at all. A greedy individual like him would be ripe for espionage recruiting. This would indicate a good bit of assisted preparation and probable continued outside help. Of course, the ability to remain "Under the radar" successfully while assigned to the space ctr would fit in better with the original version of the character. Maybe the ride through space where he became old had an effect on Smith's mind making him more befuddled unsure and illogical.
Maureen refers to Smith as an environmental control expert as she protests over John using the rockets to explore the planet below during the lead-in for Island in the Sky.
- - - - - - - I am not a fan. I just happen to enjoy movies. Fans are embarrassing.