I don't think that the Doctor literally has no interior life. But his interior life is never going to be as fully developed by the writers as another character, because the Doctor is not meant to be a psychologically realistic character. He is, at the end of the day, something of a wish fulfillment character -- an embodiment of children's fantasies about what adults ought to be like-slash-how they'd like to be as adults.
Now, because this is the 21st Century, we do get glimpses of his internal life, moments of psychological realism. But those are garnish, not the product. RTD himself noted in The Writer's Tale that Doctor Who, because it is primarily written for a family audience including children, is not a show where the characters are as well-developed and realistic as a show written for adults. Like the Marvel Studios films, these works are ultimately outgrowths of children's power fantasies.
That's why Moffat says that the Doctor has no interior life -- we can only ever get glimpses of it, because the show is not designed to develop his character to the extent it would if it were aimed at adult audiences. Add to this the necessity of keeping the Doctor somewhat mysterious and alien, and the writers end up being prohibited from developing him, or allowing him to be a particularly dynamic character. (RTD agreed with the idea that the Doctor is a static character.) The Doctor is always stuck in his eternal middle.
So I think Moffat is absolutely correct in saying that, if you cannot write about a character's internal life, and you cannot develop that character, and that character cannot grow and change on its own, then you end up having to write about the relationship the more psychologically realistic character has with that static, inaccessible character, and that relationship, seen through the secondary character's eyes, ends up being the driving force for your storytelling.
That's why Series One and Two were about the Doctor's relationship with Rose, as seen from Rose's POV. That's why Series Three was written from Martha's POV, about how she felt towards the Doctor. That's why Series Four was mostly from Donna's POV; why Series Five and Six were from Amy's (and, later, Amy's and Rory's) POV. It's also why the weakest parts of nuWho have typically been the ones where the narrative is presented from the Doctor's point of view.
Now, because this is the 21st Century, we do get glimpses of his internal life, moments of psychological realism. But those are garnish, not the product. RTD himself noted in The Writer's Tale that Doctor Who, because it is primarily written for a family audience including children, is not a show where the characters are as well-developed and realistic as a show written for adults. Like the Marvel Studios films, these works are ultimately outgrowths of children's power fantasies.
That's why Moffat says that the Doctor has no interior life -- we can only ever get glimpses of it, because the show is not designed to develop his character to the extent it would if it were aimed at adult audiences. Add to this the necessity of keeping the Doctor somewhat mysterious and alien, and the writers end up being prohibited from developing him, or allowing him to be a particularly dynamic character. (RTD agreed with the idea that the Doctor is a static character.) The Doctor is always stuck in his eternal middle.
So I think Moffat is absolutely correct in saying that, if you cannot write about a character's internal life, and you cannot develop that character, and that character cannot grow and change on its own, then you end up having to write about the relationship the more psychologically realistic character has with that static, inaccessible character, and that relationship, seen through the secondary character's eyes, ends up being the driving force for your storytelling.
That's why Series One and Two were about the Doctor's relationship with Rose, as seen from Rose's POV. That's why Series Three was written from Martha's POV, about how she felt towards the Doctor. That's why Series Four was mostly from Donna's POV; why Series Five and Six were from Amy's (and, later, Amy's and Rory's) POV. It's also why the weakest parts of nuWho have typically been the ones where the narrative is presented from the Doctor's point of view.