Categorical Imperative

Categorical Imperative was the seventh short story in the Short Trips anthology Short Trips: Monsters. It was written by Simon Guerrier. It featured the First Doctor, Second Doctor, Third Doctor, Fourth Doctor, Fifth Doctor, Sixth Doctor, Seventh Doctor, Eighth Doctor, Sarah Jane Smith, Ace, Charley Pollard, Jamie McCrimmon, Jo Grant, Susan, Peri and Tegan.