Consider a wallet, with cash in it.... it's a fine grained capabilities system. We would regularly be given $0.25 (I think?) to buy milk for lunch at school i

Consider a wallet, with cash in it.... it's a fine grained capabilities system. We would regularly be given $0.25 (I think?) to buy milk for lunch at school in 1st grade. Heck, buy the time I was 10 or so, I'd regularly be handed $20, and go and buy cigarettes for Mom with it, while she waited with my younger sisters in the station wagon outside. No matter how confused, or forgetful, or mischievous, the maximum loss was the amount handed over the in first place. It was a far safer model than handing over a credit card. Each bill is an economic token. Its a very simple model, and any side effects from using them are immediately known. If your OS were to make it just as easy to use (grant permission to the program you're running) a specific file, or folder, or network connection, and nothing else you wouldn't need to worry about virii, worms, malware, etc... you'd have decided what to open, and by default, nothing else goes along for the ride. Replacing dialog boxes with "power boxes" that act the same, except they return a capability that the OS enforces, means that most GUI applications would behave identically, and it wouldn't require much change to the code. Command line applications, on the other hand, require a new standard and uniform way to specify files, paths, etc. Even so, that would be far, far easier than spinning up a VM every time you want to run code you don't trust.