Yes, They encourage us to be isolated and afraid when we needn't be. The majority of passers by are not going to rob you, assault you, or be carrying a bomb shaped rucksack. In fact they're probably just as afraid as you are.
just a thought but are these cameras as sensitive to IR as a normal video camera (I noticed this once when filming myself with mine and using the remote, the light from the IR diode on the front of the remote was visible in the camera.) If so could this not be used as a method of jamming?

A good comment from Mike.

Norms of altruistic and reciprocal behaviour simply are almost non-existant in big cities like London and New York.

Indeed, for because these cities are so large the chance of meeting a random stranger again is low. Thus, in the equivalent of a game of "prisoner's dilemma" played once one may safely defect. Amongst a small population one will keep meeting the same people, and in repeated playings defection is not the best strategy. Thus, smaller communities will be politer, at least amongst themselves.

non-existant

Aaargh.

Pleased though I am to have something I said on quote of the day, I don't think I quite nailed it there.

Some people have questioned what tangible harm CCTV cameras do - but it is the intangible harm they represent that is sinister. The problem of trust in big cities is one kind of harm that CCTV cameras represent, but that harm only exists because of an even greater harm - and that is what is really sinister about CCTV. Even should you successfully resist assault, attempted robbery or rape on your person, the CCTV camera ensures that that will probably not be the end of the matter...

knirirr: existent - yes I do apologize.

knirirr,

That's one analysis. Another is that in the big city you meet a lot more people who appear to need your help, and that while most people will be altruistic up to a certain point, when you iterate the game the costs are multiplied to the point where you are forced to a more precise assessment. A single game in which people will usually show altruism turns them selfish when iterated.

That was my own experience on first coming to a big city. The first four or five beggars, and you feel sorry enough for them to donate. When you see ten a day, every day, you first get selective - you give if they're sufficiently entertaining or especially pathetic - and then you start coming up with reasons to persuade yourself that it's all a bad idea. 'Need' in the city is a bottomless pit and you can break yourself trying to fill it. People build those mental walls for self-protection.

I don't know about people generally, but I've never felt any more vulnerable at the sight of CCTV, precisely because it is so ubiquitous. That would make sense if they only put them up in dangerous areas - spotting them you might realised you had entered a district you probably shouldn't have - but when they're everywhere they become meaningless. The only people I feel slightly more vulnerable to as a result of seeing them are the people behind the cameras. Mostly I ignore them.

It's an ill wind that blows nobody any good.

Mike - thanks. ;-)
Pa - that is an interesting point. I think that what I've said holds true for why smaller communities are more polite (at least amongst themselves), and wonder if the effect you note is due to your relationship to the beggars in question. I'm not really sure, though.