In this groundbreaking new book, Manuel Delanda analyzes all the different genres of simulation (from cellular automata and genetic algorithms to neural nets and multi-agent systems) as a means to conceptualize the possibility spaces associated with causal (and other) capacities. Simulations allow us to stage actual interactions among a population of agents and to observe the emergent wholes that result from those interactions. Simulations have become as important as mathematical models in theoretical science. As computer power and memory have become cheaper they have migrated to the desktop.