In all his travels the Doctor has learned that most people, regardless of what they look like, tend to respond better to the carrot than the stick, which is to say they’re more cooperative when coaxed to do what he wants rather than threatened into compliance.
All, that is, except military personnel, who don’t seem to respect anyone who’s not wiling to order them around.
Oh, and Daleks, who can’t be coaxed, only follow orders given by their own kind, but are susceptible to being tricked.
Carrots, it seems, are multi-purpose. Shove one up a Dalek ray gun and…