I'm open minded. share with me why cats are the only living thing who should not be permitted to live outside. I like all animals personally, but I'm not God so I'm not going to sit around saying which ones should be allowed to live outside and which ones should be forced to stay inside.
I mean come on, how about the damage we humans do to our environment, and we do that from being INSIDE!
This doesn't make sense to me. If you're willing to be open minded, then stop engaging in hyperbole. Cats are not the "only living thing" who people would prefer to be inside rather than outside, if they're not performing a pest controlling function. People get upset when dogs are chained up and live outside 100 percent of the time as well (and certain dogs are predatory as well). I haven't ever heard people saying that horses shouldn't live outside, or plants. :P Or wild animals.
You may not be God, but when you are the owner of an animal, YOU are responsible for the impact that animal has. Cats should be belled. Dogs should be trained well and supervised around strange livestock. If you're sick of your pet gerbil or tarantula or snake, you need to find a real new home for it, not release it into the local environment.
People don't affect the environment from just being inside. The materials of their dwellings, the energy they consume to run their doodads, the wasteful or highly toxic farming methods and production methods used to bring them their cheap cheetos, endless garbage production, and demand for natural resources are what destroys the environment. Yes, we can do that inside and outside due to our culture and technology now, but I don't understand what your point is with that last statement. What is done on the inside certainly has an impact on the outside.
If you allow your cat to roam free, I can guarantee you she's probably killed for "fun" far more than the grandpa in the OP ever has. And because of her instincts, it's likely she's killed a greater variety of small creatures as well. Unless she's totally inept, just becuase you don't see it doesn't mean it doesn't happen.
Cats are not as big of a problem in our neighborhood because of our resident coyotes and bobcats--they get eaten. My kids found a cat skull and partial skeleton in our bushes this spring, probably the prey of the local bobcat who really loves our yard (it's mostly wild space with native shrubs and vegetation). So we don't have a significant feral cat population, and when I see lost or abandoned cats I try to scoop them up quickly so they don't become a snack (a friend of mine has a huge horse barn and loves to take in feral cats, or if they have a collar and/or I can feel around for a microchip I take them to the pound/humane society). I don't get to do that much anymore now that the bobcat's in residence. I don't blame the bobcat either, she's stunningly beautiful.
But why not just be realistic? Cats hunt. They are predators. They WILL prey on creatures outside, whether you like it or not. Belling them will help a bit, and is the responsible thing to do especially if you're NOT using them for pest control or making them find their own food. Between cats' real impact on local wildlife and the fact that if you have larger predators in your local habitat you're putting them at risk--that's why most humane society groups recommend indoor-only, for all the animals' protection, not because they think they're "Gods". Most people I know who have indoor-outdoor cats do so for convenience (less litter box concerns, some have even trained their cats to ONLy go outside) or because they got a cat that was already accustomed to being outside.