Watching #StarTrekTos The Enemy Within, and #Spock just made one of the worse leaps in #logic I've heard.
Something to the effect of "There is just one logical conclusion - We have an impostor on board."
While, just before, Scotty explained about the dog creature, and Scotty knew or suspected there was something wrong with the transporter before he beamed up Kirk - so it seems the leap should have been, there had been a split, or a duplicate. Not an impostor