How do we get out of here? What is the best way to release whole populations from coronavirus lockdown? Which restrictions should be lifted first, and when?
These are the questions taxing governments around the world as they try to plan for the aftermath of the pandemic. They must tread the finest possible line between restricting the further spread of Covid-19 and inflicting catastrophic damage on their economies.
The International Monetary Fund (IMF) says that the worldwide response to coronavirus would take the greatest toll on the global economy since the Great Depression of the 1930s. The Office for Budget Responsibility warns that the UK economy could shrink by a record 35% and unemployment rise by two million by June.
So the stakes couldn't be higher. Lives saved by the lockdown could be at the cost of future lives lost due to poverty and ill-health caused by a lockdown-induced recession of unprecedented severity. We are starting to realise that this is not about "lives versus the economy": it's "lives versus lives". The most impossible of choices.
There are already disturbing signs of unintended collateral damage. This week England and Wales endured a record number of deaths in a single week - 6,000 more than average for this time of year. But only half of the extra death toll numbers were attributed to Covid-19, creating concern that patients might not be seeking help for life-threatening conditions because they're scared of catching coronavirus if they go to hospital.
There are no easy answers to all this, just least worst ones. Mathematical modelling is only as good as the data it's based on, and much of that doesn't exist yet. It will probably take years, if ever, before any kind of final reckoning of the successes and failures of this nightmare period can be made.
The British Government was reportedly surprised when so many people complied with the restrictions placed on their liberty in order to preserve life and prevent the NHS from collapse.
So-called "covidiots", partying in the park, are in a vanishingly tiny minority. According to a YouGov poll, the remarkable level of public compliance with the measures stands at over 90%.
Some 48% of people approve of the current level of restrictions, while a further 44% want the rules to be even tougher.
The authorities didn't think we'd be so obedient, so willing to fall into line. But this puts them in an equally unforeseen quandary.
If most people think that the lockdown should stay in place, and a sizeable minority want us to be locked down still tighter, then how - at some point - do you persuade this frightened populace to leave their homes and venture out into the world again?
Back to work, back to school? Back - gulp - to being near one another again?
One unnamed British Government minister admitted: "There's no point announcing something before the public is ready for it." Another - also anonymous - said: "Even if you re-open schools, you can't force parents to put their kids in."
By that reasoning it would be the people, not the Government, who decide when to lift the lockdown.
Now I'm no fan of institutional authority, but the idea that something as nebulous as public opinion could be the key factor in a decision of such critical importance - one that requires the most thoroughly-researched, deeply-nuanced scientific judgments - disturbs me.
The exit strategy from lockdown is not equivalent to the Brexit referendum. It's far more significant than that, far more unpredictable, and the consequences far greater.
The world's best scientists do not agree on the nature of this new disease and the most effective ways to control it. Leading economists, too, differ on how deeply the bite of the lockdown will be felt and for how long the financial pain will last.
So, if the most highly-informed people on the planet are unsure when and how to lift lockdown, then how on Earth would we, the general public, have a clue? When it comes the decision to ease restrictions will be a calculated risk, an educated gamble, while we all hold our breath, cross our fingers and wait to see the results.
In this incredible situation there are no certainties any more. The best we can hope for is that the Government weighs up scientific guidance from as broad a range of expert voices as possible, including dissenting ones, because vigorous, robust debate has always been the mother of progress.
This is no time to put our faith in the wisdom of crowds. The science may be flawed, it may lack vital data, and it may be disputed - but right now it's all that we've got.