Beyond the usual security/freedom dichotomy we can go on for ages about, there's also a question about effectiveness. We tell ourselves that having security ca

Beyond the usual security/freedom dichotomy we can go on for ages about, there's also a question about effectiveness. We tell ourselves that having security cameras will deter criminals, because we say "well, it won't entice them will it? ". But there are two points about this: - How effective is this? If installing cameras all over the city of London stopped one person from being mugged, is it worth it? The big issue with trying to measure this is two-fold. Firstly, the notion of "stopped" is a bit hard to measure. Obviously, the number of people caught thanks to evidence on the cameras counts, but if there were eyewitnesses as well, does it still count? Inversely, what about the chilling effect brought on by the cameras? How do you count the number of people who don't even think about mugging thanks to the cameras? And who's to say that the crime isn't simply displaced? Society is pretty bad at figuring out general supply demand curves (an example: We would think that raising wages would entice people to work more, but a decent amount of arguments exist to say that after a certain wage level, increasing the wage would decrease the number of hours we work (substitution effect with leisure) (http://en.wikipedia.org/wiki/Backward_bending_supply_curve_of_labour) http://en.wikipedia.org/wiki/Backward_bending_supply_curve_o...) -How do we measure effectiveness? I get mugged and lose a $200 phone. I think I would be slightly irked by it, and quantifying this as merely a $200 loss might insult me (especially considering I'm not very used to being mugged and I would consider it a traumatic experience). A terrorist attack has a similar quantification problem, there are widespread psychological effects (even just the loss of loved ones, beyond the macro "security theater" stuff which induces circular reasoning). And the economic damage can be longterm.