No spoilers coming-up in this, BTW - the following is an abstract discussion.
I watched the 'Dr Who' 50th anniversary edition yesterday having begun to watch in 1965 with The Web Planet - I use the scare quotes to indicate that although the revived series (since 2005) has many enjoyable aspects - the modern protagonist is not the real Doctor Who since he 1. Behaves like a superhero and 2. Is a sexual being - who makes frequent smutty comments and snogs girls almost as much as did Captain Kirk.
Anyway, the episode was enjoyable in the series's now usual flashy and self-referential way, and with sweetness and depth to it in parts.
But it revealed the inadequacy of the utilitarian ethic that forms the basis for 'Dr Who' and many other similar adventure series: I mean the idea that 'The Doctor''s goal is to save lives and prevent or alleviate suffering, on the largest scale possible.
So the dilemma for much of the Day of the Doctor episode revolved around how many people's lives could/ would be saved if 'The Doctor' does X, compared with if he did Y (when both X and Y led to extremely large numbers of innocent casualties).
I think the starkness with which this dilemma was presented in Day of the Doctor showed very clearly that utilitarianism does not work as an ethical frame and leads to morally unacceptable dilemmas - when both options are wrong - and in which ethical 'deliberation' is reduced to an elite expert combination of knowledge and skill, concerned with numbers, statistics and probabilities.
(I won't say how this specific dilemma was solved/ avoided - but the method is itself specific, not general, because it leaves utilitarianism intact as the underlying ethic, without solving the serious problem of inadequacy revealed so starkly in the earlier plot.)