‘I try not to understand,’ says the Doctor. ‘It’s called an open mind.’

This is the kind of seductive and playful nonsense that makes Doctor Who such compelling drama. It’s a clever remark, has the ring of truth about it, but doesn’t bear examination. After all, understanding is what makes us unique. If we hadn’t tried to understand we’d still be living in caves.

But that’s Doctor Who. It’s not actually proper science or serious drama, even if it feels like it. The fun lies in how plausible it’s made to sound and how seriously it’s played.

‘It’s a psychic projection, or something‘ says an underling at UNIT, as the face of Missy looms out of a TV screen. UNIT’s commander is clearly irritated by ‘something’, but entirely at ease with ‘psychic projection’.

The first episode of Doctor Who Series 9 on BBC 1 on Saturday night was as good as it’s ever been. Davros and Missy (the re-gendered, regenerated Master) are back from the dead (‘Death is for other people, dear,’ says Missy), and I’m even beginning to enjoy Peter Capaldi in the role of the Doctor. What more might we ask for?

Certainly not logic. Doctor Who plays a game with us. For the nerds who know the twist, turn and dialogue of every episode it weaves an apparently consistent fabric out of everything that’s ever happened and everything the Time Lords have ever said about themselves. It’s a complete and coherent account of their planet, their history and their nature. Whatever happens there’s always an apparently plausible reason that makes sense within the structures and assumptions of the show. After all, we want it to make sense. We want it to be real. That’s drama.

A mixture of solemn moralising, fanciful sci-fi, heroism, pathos and horror, in fact Doctor Who has it all. What it lacks, of course, is real logic. The logic of time travel is one of Steven Moffat’s specialities (remember the brilliant and prize-winning  Blink from 2007), and he manages it with incomparably greater brilliance and humour than Back to the Future ever did. But whilst, again in this episode, he’s having fun with the future causing the past, he’s also having fun ignoring the more basic and inconvenient logical problems of time travel (can you imagine, I actually studied some of the logical issues of time travel during my philosophy course at Oxford?).

The central fact of Saturday’s episode is that Davros is dying, but if you’re a time traveller with no particular commitment to any particular time Davros is always dying, and always being born. Why the call from the future or the past should come ‘now’ as opposed to ‘then’ is anyone’s guess. But who cares? The fun is in half believing it makes sense.

Another problem. ‘Where is the Doctor?’ doesn’t make sense, either. The Doctor belongs nowhere at any particular time, or may be in more than one place at once if he’s wherever he is  ‘at this moment’ more than once in his own timeline. Indeed, we’ve seen him in one place more than once.

But it’s churlish to find fault. Half-logic, half-plausibility, half-science, half-seriousness is the point of it, and I’ve suspended my disbelief every Saturday since the 1960s when the Doctor first appeared.

There’s half-morality too. Hackneyed though they are, the moral dilemmas these stories raise seem real enough at the time. The troubled figure of the Doctor (is he really a good Time Lord?) wrestles with moral choice as any realistic hero might, and in Doctor Who there isn’t always a good choice. (Star Trek‘s Captain Kirk, by contrast, possesses a moral compass (an American one, obviously) that never fails to point him in the right direction.)

“if someone who knew the future pointed out a child to you and told you that that child would grow up totally evil, to be a ruthless dictator who would destroy millions of lives, could you then kill that child?’

A flashback to Tom Baker’s Doctor of the 1970s illustrates the dilemma the current Doctor faces in this first episode. Should he rescue Davros the child, trapped in a ‘hand mine’ field, knowing, as he does, what Davros, inventor of the Daleks, will become? And does he rescue him, or abandon him? This first episode leaves us guessing.

I suspect we’re in for a morally subtle logical twist. It will be because the Doctor abandons him that Davros becomes the monster he becomes.

Such (fanciful) moral dilemmas (morality on holiday, as Wittgenstein might say) remind me of a 1975 science-fiction story Let’s Go to Golgotha, which describes a group of tourists time-travelling back to that moment when Pontius Pilate asks the crowd to choose between Christ and Barabbas. Cautioned about changing history and against standing out from the crowd, they chant ‘Barabbas’, only to realise that everyone in the crowd is a time tourist like them.

This first episode of the new series also shows Peter Capaldi growing into the role, or is it that we’re getting used to him? Anguish is what he does best, and in this new series they’re piling it on.  I can’t wait for next Saturday.