Sefer ha-Ikkarim

Sefer ha-Ikkarim ("Book of Principles") is a fifteenth century work by rabbi Joseph Albo, a student of Crescas. It is an eclectic, popular work, whose central task is the exposition of the principles of Judaism.

Agreeing with Simeon ben Joseph of Lunel (i.e.: Duran), Albo held that there are three basic principles (ikkarim) that are necessary for the divine law to exist:

1. the existence of God,
2. the revelation of God,
3. the reward and punishment of God.

From these three principles, Albo posited that there are eight derivative principles (shorashim):

1. From the existence of God derives the principle of God's unity
2. From the existence of God derives the principle of God's incorporeality
3. From the existence of God derives the principle of God's timelessness
4. From the existence of God derives the principle of God's perfection
5. From the revelation of God derives the principle of God's omniscience
6. From the revelation of God derives the principle of God's prophecy
7. From the revelation of God derives the principle of the authentication of God's prophet
8. From the reward and punishment of God derives the principle of individual providence.

The denial of these principles, no less than the denial of the first three, makes one a heretic (kofer be-ikkar). It is understood in Albo's work that there are three kinds of law: natural law, conventional law, and divine law. Natural law is the same for all persons, times, and places; conventional law is ordered by a wise judge in accord with reason; divine law is given by God through a prophet.