The question of airport capacity around London is complicated because it's about so much more than just transport. It's about hopes and fears for the future - as well as noise over people's houses. And nothing seems right.
Consider the most radical plan: a brand new airport in the Thames estuary to replace Heathrow.
It sounds crazily grandiose. But to reject it on the grounds that 'enough is enough', that Heathrow, however unpleasant its impact on London, will be the capitol's main airport for ever, is a kind of giving up. It's like an elderly person deciding never to buy another car because they've done most of their driving, and that the old one will probably do, and will certainly save some money and bother.
Shouldn't we, instead, be confident about the future and press on boldly, even if we're not sure how we'll pay for this massive project - just because to do otherwise is a blatant vote of no confidence in the lives of our children and grandchildren. After all, planes are already quieter and more fuel-efficient than they were, and no doubt scientists will come up with ways to deal with the other environmental problems in time.
Of course an estuary airport will be even more expensive than anyone thinks now. But if it gets built, nobody will really mind: it'll create work for thousands, support British companies, and be a symbol of a new, dynamic Britain, one fully intending to be the life and soul of the global community for the rest of this century, as it was in the last. The Channel Tunnel hasn't been a resounding financial success, but nobody now says it would have been better to have saved the money and forfeited its advantages.
As for a third runway at Heathrow, well, I'm in at least two minds about that. Living just south of the flightpath to Heathrow's existing southern runway, I don't appreciate the landings in the early hours. Nor do I like having to raise my voice to talk to friends in the garden on a summer afternoon.
But if a third runway was built, it would be north of the current northern runway, pretty much outside earshot to me. Perhaps it would spread the aircraft noise more thinly over a wider area. So from a purely selfish point of view, it might actually have advantages in my neighbourhood (a fact that never features in the campaigning of our local Lib Dems.) Of course, the idea is for more flights to use the airport, so things might not change much.
And it's quite handy to be able to drive to Heathrow in around 30 minutes (on a good day). And it probably brings prosperity to West London and the Thames Valley.
But all that's parochial stuff. We need to make the decision on the big picture - one beyond 'my backyard', beyond party politics, and even beyond the borders of our country.
I think I just might be persuaded by a more imaginative, more positive line by the Greens. They'd need someone with real character and conviction. If I were their speechwriter, this would be my suggestion:
"We all know that economic growth and commercial expansion cannot go on for ever: we live on a planet of limited size and resources. The mystery is why that isn't yet acknowledged by politicians.
It might make sense to spend £50 billion on a new airport, transferring Heathrow's business to the East of London if you believed that air transport will inevitably expand, and that if we don't do it, the Netherlands or France will jump in and become a more important international hub, and that that would be terrible for London and Britain as a whole.
But air travel can't expand for ever. Its relative cheapness today is the consequence of some peculiarities of taxation (where no country wants to deter airlines by taxing them more than its competitors). The costs we pay certainly don't reflect the real price in terms of noise, pollution and global warming.
But we don't need to be negative about this. As politicians, we should be brave enough to say that in the future, our ambitions should be not just for more things, but for different things. That in this country we are lucky that most people already have homes to live in, food to eat, healthcare, education, and even holidays. That justice is administered without much corruption and that elections are for the most part fair. That politicians leave office without an argument if they are voted out.
But that all these achievements, which many other countries are still striving for, give us a responsibility to set a new course that others may also follow if they choose. And that course takes us off the road of consumerism and materialism onto one in which other values are our priorities, values which are independent of economic growth and which take for granted - because we have actually reached that point - a degree of satisfaction with our material situation, and move us gently forward to thinking about the quality of life.
If we stopped buying, or made more expensive, a lot of the stuff we don't need - from mineral water to disposable furniture and outsized conservatories - and didn't waste so much - on food, energy and packaging - and didn't go to so many places in such a hurry that we haven't got time to think about the experience for longer than it takes to get back from the airport, what could we do with the time and money we'd liberate? We could learn more, exercise, celebrate, communicate, create, grow things. We could teach, help those who need helping, spend time on things we are too rushed to do properly and on doing not much at all - like our hunter gatherer ancestors did before the work ethic made doing nothing look like sponging off other people.
And we wouldn't need to fly so often. But it wouldn't be a negative decision: it would be part of a much bigger, positive one.
I just might if that leader appeared.