What in principle would justify the scope of the surveillance revealed by the Snowden leak? Would it be enough, for example, if it could be shown that a specific potential act of terrorism had been prevented by, and could only have been prevented by, the full breadth and depth of what we now have learned is the playing field of the security services?

We should hesitate before we stray off the touchline. The idea that public safety, the safety of the innocent, is an absolute which trumps every other consideration, is tacitly abandoned in the way we live.

Nobody would be killed on the roads if the speed limit were 10 miles an hour. Flying would be safer if airport security demanded body searches with no exceptions and the examination of every item in every piece of luggage. On the matter of surveillance in general we have, without much discussion, learned to live with almost blanket surveillance by CCTV in our towns and cities. As a result thousand of crimes, including murder, have been solved and perhaps many more prevented. But how many more would there have been if we doubled the number of cameras, or increased them tenfold, a hundredfold?

Between that and the surveillance we are now talking about there is a qualitative as well as a quantitative difference which hardly needs pointing out. The cameras are in public places, they are not in our houses or our cars or even in our gardens. By contrast, the world of surveillance operated by the people we pay to guard us exceeds the fevered dreams of the Stasi.

Even so, let's go carefully here. The Stasi were not dealing with a global threat of murderous malignity. The constituency of everything to be feared has also been altered dreadfully by a technology which vastly underwrites a capacity for evil as it does the capacity for the social good. As for our spooks, I know what I want from them. I want them to eavesdrop on the phones, the emails, on every tap of the keyboard of anybody who comes under suspicion. Somebody somewhere has the responsibility, indeed the necessary duty, of identifying those who bear us ill. I would like there to be secret cameras in their houses. I would applaud the technological means to survey and interpret every breath they take. However, metaphors for the expansion from this selflimiting scope beggar the imagination. If the world of secrets is its own universe, here we have an expansion of the universe which brings to mind something cosmological.

It had to happen. When all that possibility of expansion became available the spooks were going to avail themselves of it as naturally as night follows day.

Imagine that some law enforcement agency received reliable information that a drug lord or a suicide bomber or a murderer on the run was at this moment hiding out in … let's say Beaconsfield. Should we have a problem with the idea that for the next few days there was going to be blanket electronic surveillance on every message or metadatum flowing in and out of Beaconsfield? Would I get worked up about that? Not much. How about Swindon? Manchester? You can see where this is going. At some point in the expansion there is a phase transition our attitude will undergo. Something that seemed OK no longer seems OK.

The impulse we are now experiencing goes back as long as we have been living in groups. How much do we owe each other? How much of our very self, our individuality, our privacy, our subjective and autonomous freedom to live as utterly unique human beings, is up for grabs on the say so of whoever is making the rules for the group, not withstanding that the rulemakers have been validated by all of us?

It is no light matter to put in jeopardy a single life when it is the very singularity of each life which underpins the idea of a just society. But it appears to me that our masters are in the grip of the delusionary nightmare of completeness: the complete annihilation of every rogue bacillus. It's as if there is a belief that in the end the virus has no riposte, that there cannot be and will not be a means to evade blanket security if it is blanket enough.

What is the society we wish to protect? Is it the society of complete surveillance for the commonwealth? Is this the wealth we seek to have in common - optimal security at the cost of maximal surveillance? Not that anybody asked us. It takes a brave newspaper to have forced the question into the open.