"Leadworth or the TARDIS: which is real, and which is the dream?"
It's an unanswerable question: but it isn't really the question which the Dream Lord is asking.
He's not asking "Which is real" but "Which would Amy prefer to be real?" Faced with a free choice between Leadworth and the TARDIS, which reality would she chose? (Clues in the title, I suppose.)
The answer is never really in doubt. New Who has consistently treated romantic happiness as the ultimate Good. Once the question has been articulated – once it has been made clear that "Leadworth or the TARDIS?" really means "the Doctor or Rory?" we know pretty clearly which way Amy will swing.
In fact, the question isn't even "Does Amy love Rory?" It's more "How will Amy realise that she loves Rory?" or more specifically "How will Amy be brought to the point where she can tell Rory that she loves him?" This is also going to be a large part of the plot of the one in the flat: one human coming to the point where he can say those three little words to another human. The rest of the story -- pollen, dream lord, philosophical riddle, emotional conundrum – is all plot machinery to bring Amy to this point.
There are a lot of good moments along the way. The idea that for Amy (as well as for us) the Doctor "represents" childhood is made explicit. Rory says that they can't stay on the TARDIS indefinitely, because sooner or later they have to grow up. "Do we?" she replies. The Dream Lord repeats the same thing to the Doctor, but puts a creepy twist on it. The Doctor is an incredibly old person playing at being young by always choosing the company of young people. When the Doctor asks what Rory and Amy do in boring Leadworth "in order to stave off the self harm" and Rory replies "we live".
So: that's the point of the story, is it? Amy's choice is really between growing up and not growing up: between being Amy and being Amelia. It's the Peter Pan dilemma: remain a child, and be lonely forever; or grow up, and be bored forever. "He had ecstasies innumerable that other children can never know, but he was looking through the window at the one joy from which he must be forever barred." Remind you of anyone?
It's a silly question, and it always has been. As a matter of fact, and with the exception of a very small number of brain damaged individuals, "never growing up" is not actually an option. And the TARDIS is (whisper it softly) fictitious. Asking an adult to consider what they would do, if, like Peter Pan, they were offered the chance of "never growing up" is only a vivid and rhetorical way of asking them to consider what "growing up" (or "being a child") means. If Peter Pan and Doctor Who "mean" imagination and creativity and the perception of beauty and having fun and all that stuff about the wonders of the universe that Sarah Jane goes on and on about at the end of every. damn. episode. – and if "being a grown up" means losing all of that – then surely every relatively well balanced individual would go for Never Never Land every time? But it's a false dilemma. The dichotomy between "being an adult" and "having fun" has been forced on us by psychologically damaged individuals like the Dream Lord and Mr. Darling.
Except... The one thing which adults definitely have which children definitely do not have is the capacity for romantic love and....you know....sex. And it may be that faced with a straight choice between "the ecstasy of sex" and "all other kinds of ecstasy", most adults would forgo the sunsets and the daisies and keep the squelchy stuff, please. (When he was researching his book Talking Cock, Richard Herring discovered that an overwhelming majority of men would rather be blinded, crippled or brain-damaged than have their thing cut off.) [*] Maybe that's why Amy's choice is so specifically presented as TARDIS vs Marriage; Doctor vs Baby. Maybe that's why, since 1965, it's always been wedding bells that breaks up the happy TARDIS gang. When Susan Foreman fell in love the First Doctor cast her out of the TARDIS. She and her earthling boyfriend went off hand in hand. With wandering steps and slow, I shouldn't wonder.
But even this isn't really a choice, is it? You could choose to be celibate: that's an option; but that won't in itself make the universe more magical. It won't even make Easter Eggs taste like they did when you were six. The myths of Eden, or Never Never Land and of the TARDIS aren't really about choices. They are descriptions of the way things are. "When you were a kid, life seemed to be more happy and carefree, and the colours were brighter and the ice cream more delicious. All that is gone forever. But on the plus side, you get to have orgasms!"
The first person to mention nylons, lipsticks, or invitations will be ejected by security.
O.K. I admit it. I'm over-thinking. Whenever the Doctor asks a companion into the TARDIS, whether it's William Hartnell talking about another world in another sky, or Christopher Eccleston saying "Wanna come with me?", the question is really being director at us viewers. "Going with the Doctor" means "Watching a really quite thrilling TV show". So "leaving the TARDIS" means "not watching your favourite TV show any more." "You can't stay in the TARDIS forever, one day you'll have to grow up and get a life" boils down to "Eventually you'll have to stop reading books about unicorns and start reading books about kitchen sinks." Romance vs realism; escapism vs serious literature.
This seems to have been the kind of thing which Mr Stephen Fry had in mind: a liking for Winnie-the-Pooh automatically and necessarily precludes a liking for Middlemarch. And if we define television which is "surprising, savoury, sharp, unusual, cosmopolitan, alien, challenging, complex, ambiguous, possibly even slightly disturbing and wrong" as "adult" and drama which is fun and escapist as "childish"; and if the only two options on the table are a world where all television is "adult" and a world where all television is "childish" then I suppose we'd all go for the former. If the waves on the desert island really did wash away every one of my DVD boxed sets except one, I'd grab Wagner's Ring Cycle before I grabbed Star Wars [**].
But it's the falsest of false dilemmas. Very few people want to eat snail porridge and salmon liquorice every night of the week: but it doesn't follow that they subsist entirely on big macs and deep fried mars bars.
It's quite interesting that Steven Fry should use "adult" as a term of approval. Adults like all kinds of entertainment. They read Mills and Boon romances. They read Agatha Christie whodunnits. They read Zane Grey westerns, Black Lace sex stories and Andy McNabb memoirs about war and torture and field latrines. I don't think that books of that kind are particularly challenging, complex or ambiguous. I think they are safe, simple and straightforward. But wouldn't describing them all as "childish" be a little...well....adolescent?
"Which is the dream: the TARDIS or Leadworth?"
Of course it's an unanswerable question. So of course the Doctor answers it. They are both dreams. That's the trap. When faced with the choice between two mutually exclusive alternatives, always choose the third one.
[*] I'm not absolutely sure about this. Suppose NASA said tomorrow "We want volunteers, aged about 20, to travel to Alpha Centuri and contact the aliens who we are now pretty sure live there, and then come home and report. Only catch is, it's a small ship and a forty year round trip: you'd effectively be taking a vow of lifelong celibacy." I'm guessing they'd still have one or two volunteers. Mars is worth any number of grandchildren.
[**] Although I might be prepared to negotiate e.g if I forgo the Norns and the riddle game can I keep "A New Hope"?