Three Kinds of Idealization

Philosophers of science increasingly recognize the importance of idealization, the intentional introduction of approximate or false information into scientific theories. The literature of the past twenty years contains a number of accounts of idealization which provide differing characterizations of this practice and differing justifications for it. There is thus little consensus on some of the most basic questions about idealization, such as: What exactly constitutes idealization? Is idealization compatible with realism? Are idealization and abstraction distinct? Should theorists work to eliminate idealizations as science progresses? Are there rules governing the rational use of idealization, or should a theorist’s intuition alone guide the process? Despite the variation in characterizations and justification of idealization, some consensus has clustered around three types of positions, or three kinds of idealization. But as with many other dimensions of scientific practice, what scientists call idealization and how they justify the practice it is multifaceted. I will argue that the reason the philosophical literature has sustained three kinds of accounts is because all three kinds of idealization play important roles in scientific research traditions. There is no single purpose for idealization and hence there is not a single set of rules that theorists ought to follow when idealizing. While all three kinds of idealization can be found in scientific practice, they share enough in common that they can be characterized and studied in a unified way. The key is to focus not just on the practice and products of idealization, but on the goals governing and guiding it. I call these goals the representational ideals of theorizing and although they vary between the three kinds of idealization, attending to them gives a more unified picture of the practice.