Bruce Schneier describes our need to:
In today’s society, we need to trust not only people, but institutions and systems. It’s not so much that I trusted the particular pilot who flew my plane this morning, but the airline that produces well-trained and well-rested pilots according to some schedule. And it’s not so much that I trusted the particular taxi driver, but instead the taxi licensing system and overall police system that produced him. Similarly, when I used an ATM this morning — another interesting exercise in trust — it’s less that I trusted that particular machine, bank, and service company — but instead that I trusted the national banking system to debit the proper amount from my bank account back home.
Here’s how I like to look at it. All complex ecosystems require cooperation. This is true for biological ecosystems, social systems, and sociotechnical systems. Also, in any cooperative system, there also exists an alternative parasitical strategy. Examples include tapeworms in your digestive tract, thieves in a market, spammers on e-mail, and people who refuse to pay their taxes. These parasites can only survive if they’re not too successful. That is, if their number gets too large or too powerful, the underlying system collapses.