Invariance

This chapter explores the notion of invariance, which is of central normative importance in causal reasoning and is also central to its descriptive characterization, as shown in subsequent chapters. The invariance of a causal relationship has to do with the extent that it continues to be operative across various sorts of changes—in background conditions, changes in the distribution of initial conditions, and different micro-realizations of a cause, to describe just a few of the possibilities that are considered. Invariance is distinguished from exceptionlessness and needs to be understood against the background of our epistemic and calculational limitations.