A cat is pretty well suited to a natural environment which doesn't have much of human interruptions. They are much aware of dangerous species and etc. but what they are not aware of is manmade things like rat poisons, highways and how much speed does a vehicle have etc. So, this creates much safer zone in your house for a cat.

Because of that an outdoor cats? lifetime has shorten to 2-4 years while lifespan of an indoor cat is 14-18 years. In many states it is illegal to let your cat be an outdoor wanderer. When nature intended for cats to live in outdoors, it wasn't a time which had traffic, poisons or cat haters. Also there are several deadly and serious diseases your cat can catch from other animals. Thousands of cats get injured or dead by car accidents every single day. So don't let your cat become one of them.

On the other hand you cant? make an outdoor cat and indoor one suddenly. Some of them are used to outdoors. Taking care of outdoor cats will be much easier than indoor cats. Because indoor cat happen to get stressed much easily and we have to accept, taking much care in indoors or anything else will not make them live forever. They will die someday just as we humans. So let them enjoy their lives. So if you are living in an environment where is safe from above dangers and if it is legal, adopt an outdoor cat if you like.

Remember you also cannot change an indoor cat into an outdoor one in a sudden, since he is not even aware of the natural dangers for a long period. So keep your indoor cat indoor and outdoor cat outdoor and either way take good care of them and protect them.