I suggest you read the PA statutes. What you seem to be referring to is the use of lethal force outside the home. The law regarding private residences is different and was recently amended to extended "inside your home" to include patios, decks and entrances, it also removed the "retreat" proviso.
Having a carry permit requires demonstration of knowledge of the laws regarding firearms. Yes, I have one.

Please know what you are talking about before bashing people.