Funakoshi developed Shotokan with the intention to develop an art which built not only physical strength but mental strength, integrity, and self control. This is most obviously seen in the Dojo Kun:
In English (roughly) it states: 1. Seek perfection of character 2. Be sincere and honest. 3. Show strong spirit. 4. Practice courtesy 5. Control bad temper. There are many other interpretations of this, but they all mean essentially the same thing.
Funakoshi also had a set of rules for Karate students of his Dojo which are still followed today. He called these rules the Niju Kun:
1) Karate is not only dojo training. 2) Don't forget that Karate begins with a bow and ends with a bow. 3) In Karate, never attack first. 4) One who practices Karate must follow the way of justice 5) First you must know yourself. Then you can know others. 6) Spiritual development is paramount; technical skills are merely means to the end. 7) You must release your mind 8) Misfortune comes out of laziness. 9) Karate is a lifelong training. 10) Put Karate into everything you do. 11) Karate is like hot water. If you do not give heat constantly it will again become cold. 12) Do not think you have to win. Think that you do not have to lose. 13) Victory depends on your ability to tell vulnerable points from invulnerable ones. 14) Move according to your opponent. 15) Consider your opponent's hands and legs as you would sharp swords. 16) When you leave home, think that millions of opponents are waiting for you. 17) Ready position for beginners and natural position for advanced students. 18) Kata is one thing. Engaging in a real fight is another. 19) Do not forget (1)strength and weakness of power, (2)expansion and contraction of the body, (3)slowness and speed of techniques. 20) Devise at all times.
- One of Funakoshi's main beliefs was that Karate was to be used as self-defense only. Even on Funakoshi's grave the words "Karate ni sente nashi." or "There is no first attack in Karate." are engraved.
These Kuns are the basis of Shotokan philosophy. Each school may have their own philosophy, but they all branch from this.