With Blackjack being a game which lends itself to deep-thinking it should come as no surprise that Blackjack Philosophy is a well developed part of the game. Over hundreds of years while the game has been played Blackjack players and aficionados have caused this area of the game to grow. They isolated different parts of the games and discussed them at length. So theory developed what to do is certain situations and scenarios.
Essentially Blackjack is a very simple game. You have to get as close to 21 without going over and then hope to beat the dealer. Ironic then that given this how much has been written and said about the game. With it being the casino game where the player has the best long-term chance of winning everything makes a difference.
Blackjack Philosophy is covered at length at LuckyBlackJack.com with the following pages on the topic: