Proposition 2. TIT FOR TAT is collectively stable if and only if, w is large enough. This critical value of w is a function of the four payoff parame… - Robert Axelrod

The social influence model illustrates three fundamental points:
1. Local convergence can lead to global polarization.
2. The interplay between different features of culture can shape the process of social influence.
3. Even simple mechanisms of change can give counterintuitive results, as shown by the present model, in which large territories generate surprisingly little polarization.

The cooperative exchanges of mutual restraint actually changed the nature of the interaction. They tended to make the two sides care about each other's welfare. This change can be interpreted in terms of the Prisoner's Dilemma by saying' that the very experience of sustained mutual cooperation altered the payoffs of the players, making mutual cooperation even more valued than it was before.

In the future it would be good to use these conceptual and statistical developments to answer some new questions suggested by the model. For example, the dynamics we have seen in the tribute model suggest the following interesting questions:
a. What are the minimal conditions for a new actor to emerge?
b. What tends to promote such emergence?
c. How are the dynamics affected by the number of elementary actors?
d. What can lead to collapse of an aggregate actor?
e. How can new actors grow in the shadow of established actors?