Power in Motion
The axioms of quantitative realism are based on the notion that power is a fluid-like substance that flows through a network of agents. Agents can use their power to make others more powerful or, conversely, to diminish their power. In choosing how to deploy their power, agents alter the course of its movement. Consequently, power is both a stock (a quantity possessed by an agent) and a flow (a quantity in motion between agents).
Power structures are not static but evolve in time due to two interacting processes. First, as depicted above, the relationships among the agents cause power to flow through the network, affecting agent strength levels: some agents get stronger, and others get weaker. Second, agents alter their foreign policies in a ceaseless quest to improve their position within the power structure. Agent sizes change as a result of their relationships, and in response the agents readjust those relationships, in an unfolding strategic dance ad infinitum. The first process entails a change to the vertices of a power structure; the second to its edges. The interplay of these two processes is what drives the model and brings power structures to life in ways that resemble, in abstract form, the kinds of power struggles that we see in the real world.
In this section, we examine the first process: how agents grow stronger or weaker as a function of the relationships they have with other agents. We call this the law of motion. After describing this movement of power and illustrating it visually, we consider refinements that take into account physical distances among the agents and their possession of scarce resources. Later, we explore the second process: the incentives that shape how agents alter their relationships with each other — in other words, how they determine their foreign policies.