1) The vulnerable, those who can't look after themselves, need more help than most.
2) If certain behaviours help to keep all of us safe, they should be incentivised.
3) If vital infrastructure and services are at risk of collapse, and the market cannot bear the cost of restoring them, those costs should be socialised, or shared between all of us, with the wealthy shouldering the lion's share.
Here I am thinking of the genuine risks that, if, as the government has said, a fifth of employees will end up self-isolating (and that may be an understatement) maintaining everything from payment systems to broadband will become challenging (I am not being alarmist - business leaders have shared their fears with me about the risk of systemic collapse).
4) The government and Bank of England should be the insurer of last resort for companies - which does not mean keeping all businesses on life support, but does mean propping up those whose loss would do most harm to the UK's productive potential and providing emergency cheap credit to others that can demonstrate their underlying viability and resilience.
As one Tory minister put it to me, these principles imply that Boris Johnson will almost certainly have to oversee a government that for a good year or maybe longer will look quite socialist.
"We'll find ourselves implementing most of Jeremy Corbyn's programme" is how he put it.
As I mentioned, the Treasury and Bank of England will find themselves having to play God in respect of deciding which businesses to save.
And the simplest way to make sure no one goes to work and spreads the virus when they should be self-isolating is to introduce that most debated of modern welfare concepts, the universal basic income - which gives an entitlement to everyone to a minimum income.
Even Tories are talking to me about the probable need for a temporary universal basic income, to get round all that confusion of which welfare payments kick in to whom, and to save many younger people in particular falling through the existing state safety net.
Right now, what is required is decisiveness and simplicity in response. And, probably, over coming months, hundreds of millions of pounds in business grants, new credit and additional welfare payments.
When we hear from the Chancellor Rishi Sunak later today, I slightly doubt he will be ready to announce the full-blooded introduction of Corbynism, even if his colleagues tell me that is our inescapable - if perhaps temporary - destiny.
But he is already aware that his budget of last week is a near irrelevance.
The economy is slowing fast. A recession - a global recession - is unavoidable.
So tax revenues are already declining and welfare payments will be on a sharply rising path, via what are known as the automatic stabilisers.
A deficit of anywhere between 6% and 10% does not feel remotely improbable.
In other words, even if Sunak did not tonight follow the lead of Germany and France by offering significant state support running to many ten of billions of pounds to an ailing private sector and individuals facing unemployment, this year's public finances would be wrecked.
So surely better to wreck the public finances with a deliberate remedial purpose than simply let the tsunami take its devastating course.
Coronavirus: Everything you need to know