GALILEO GALILEI AND THE INQUISITION, I
In 1633, the great astronomer and scientist Galileo Galilei was under consid- eration for interrogation by the Inquisition. The Catholic Church contends that in 1616 Galileo was ordered not to teach and support the Copernican theory, which is that the earth revolves around the sun, and furthermore that he violated this order with his latest book, The Dialogue Concerning the Two Chief World Systems. The situation to be modeled is the decision of the Catholic Church regarding whether to bring Galileo before the Inquisition and, if it does so, the decisions of Galileo and the Inquisitor regarding what to say and do.
The players are Pope Urban VIII, Galileo, and the Inquisitor. (Although there was actually a committee of Inquisitors, we’ll roll them all into one player.) The extensive form game is depicted in FIGURE 2.3. Urban VIII ini- tially decides whether to refer Galileo’s case to the Inquisition. If he declines to do so, then the game is over. If he does refer the case, then Galileo is brought before the Inquisition, at which time he must decide whether to con- fess that he did indeed support the Copernican case too strongly in his recent book. If he confesses, then he is punished and the game is over. If he does not confess, then the Inquisitor decides whether to torture Galileo. If he chooses
FIGURE 2.3 Galileo Galilei and the Inquisition
Urban VIII
Urban VIII 3
Galileo 5
Inquisitor 3
Galileo
Galileo
Do not confess
Do not confess
Do not torture
Confess
Confess
Inquisitor 5
3
4
2
4
2
4
1
5
1
2
1
Do not refer
Refer
Torture
2.2 Extensive Form Games: Perfect Information 23
To complete the extensive form game, payoff numbers are required. There are five outcomes to the game: (1) Urban VIII does not refer the case; (2) Urban VIII refers the case and Galileo initially confesses; (3) Urban VIII refers the case, Galileo does not initially confess, he is tortured, and then he con- fesses; (4) Urban VIII refers the case, Galileo does not initially confess, he is tortured, and he does not confess; and (5) Urban VIII refers the case, Galileo does not initially confess, and he is not tortured.
In specifying payoffs, we don’t want arbitrary numbers, but rather ones that accurately reflect the preferences of Urban VIII, Galileo, and the Inquisitor. Galileo is probably the easiest. His most preferred outcome is that Urban VIII does not refer the case. We’ll presume that if the case is referred, then Galileo’s preference ordering is as follows: (1) He does not confess and is not tortured; (2) he confesses; (3) he does not confess, is tortured, and does not confess; and (4) he does not confess, is tortured, and confesses. Galileo was a 69-year-old man, and evidence suggests that he was not prepared to be tortured for the sake of principle. Urban VIII is a bit more complicated, be- cause although he wants Galileo to confess, he does not relish the idea of this great man being tortured. We’ll presume that Urban VIII most desires a con- fession (preferably without torture) and prefers not to refer the case if it does not bring a confession. The Inquisitor’s preferences are similar to those of Urban VIII, but he has the sadistic twist that he prefers to extract confessions through torture.
So, what happened to Galileo? Let’s wait until we learn how to solve such a game; once having solved it, I’ll fill you in on a bit of history.
not to torture him, then, in a sense, Galileo has won, and we’ll consider the game ended. If the Inquisitor tortures poor Galileo, then he must decide whether to confess.
Galileo before the Inquisitor
H U
LT O
N A
R C H
IV E/
G ET
TY IM
A G
ES
24 CHAPTER 2: BUILDING A MODEL OF A STRATEGIC SITUATION