The four causes of hypnosis.

Aristotle's model of comprehension involves the description of a phenomenon and identification of its efficient causes (triggers), material cause (substrate), formal cause (models of structure), and final cause (function). This causal analysis provides a framework for understanding hypnosis and the hypnotic state. States are constellations of parameters within specified ranges; they name, but do not explain, a phenomenon. Concerns about reification of states are matters of semantics and pragmatics, not ontology. Isolation of efficient causes (e.g., procedure, context, social variables) is but one component of understanding. Experimental, technical, and conceptual advances have carried us into a century where the substrates and functions of hypnosis may be represented in synoptic theories that comprise all 4 causes of hypnosis.