Thesis: Ph. D. in Linguistics, Massachusetts Institute of Technology, Department of Linguistics and Philosophy, 2015.Cataloged from PDF version of thesis.Includes bibliographical references.This work addresses questions about causation and evidence: How can we learn what causes what? Can we get evidence for objects that don't cause anything? And what is the evidential relationship between events in a causal loop? Structural equations accounts of causation seem to provide a good basis for discovering causal relationships through observation. But these accounts can sometimes give the wrong verdict in cases that are structurally similar to cases that they do get right. Distinctions between default and deviant states, and between more and less ...