What is Gamaliel's principle?

Answer 1

In Acts 5:34-39 Gamaliel's principle can be found. After Stephen defends himself before the Sanhedrin Gamaliel decides that "For if their purpose or activity is of human origin, it will fail. If, on the other hand, it is from God, you will not be able to stop these men; you will only find yourselves fighting against God."(39)

Although at the time it did convince the Sanhedrin to let Stephen go, the crowd went on to stone him to death. At the time the principle held true in the court room, but it can not always be said to be reliable.

Answer 2

Gamaliel's Priciple is a philosophical concept derived from a speech attributed by Acts of the Apostles to Gamaliel I (Acts 5:34):

Then stood there up one in the council, named Gamaliel, a doctor of the law, high in reputation among all the people, and he said unto them: Take heed of yourselves what ye intend to do as touching these men. For before these days rose up Theudas, boasting himself to be somebody; to whom a number of men, about four hundred, joined themselves; he was slain, and all, as many as obeyed him, were scattered and brought to nought. After this rose up Judas of Galilee in the days of the taxing, and drew away much people after him; he also perished, and all, even as many as obeyed him, were dispersed. And now I say unto you, refrain from these men, and let them alone, for if this counsel or this work be of men, it will come to nought: but if it be of God, ye cannot overthrow it, lest haply ye be found even to fight against God.

The Principle is that the long-term course of future events - consequent to a particular antecedent event - is strictly correlated with the truth of the antecedent event. Gamaliel is portrayed as saying that if what the apostles were teaching was untrue, the work of men, it would come to nothing, but if it was the work of God, then nothing the Sanhedrin could do would stop it.

Although attributed by Acts to Gamaliel, the Jewish sage could not really have been responsible for these words. He mentions Theudas' revolt and "after him Judas the Galilean." If this Sanhedrin session took place around 35 CE, Theudas' revolt had not yet taken place, and the revolt by Judas the Galilean had taken place thirty years before.

The Gamaliel Principle is is somewhat parallel to Pascal's Wager, which on pseudo-mathematical grounds, states that a man ought to bet on the existence of God, because if he is wrong it does not matter, whereas if God really does exist, then the 'return' on his wager is infinite.