<p>In all the sciences, words or concepts are created or adopted and then inserted into theoretical arguments to bridge gaps in the reasoning. Such concepts are the source of “leaps of imagination” that are a common part of scientific advances. The concepts are not chosen at random. In theorizing, we often find a point where those causal processes we understand do not help us get to the next step in our reasoning. But we often know a great deal about what the properties of the unknown causal processes must include. I will argue that the term “emergence” serves this function in economics. It represents the appearance of a phenomenon that cannot be explained by the known causal processes that we are studying. Similar concepts permeate many varieties of economic theorizing. This paper focuses on “emergence” as an example of the characteristics of successful theorizing about such gaps in causal explanations by exploring three approaches to explaining how complex organizations in society come about. The approaches are analogies to the physical sciences, mathematical modeling, and abductive inference. The conclusion is that applying all three methods is likely to be fruitful in developing insights into emergence in economic (and social) systems.</p>