Abstract
An error is a process whose stages execute out of sequence: a later stage executes before the earlier stage it depends on has delivered. Any judgment, computation, diagnosis, or inference proceeds through four ordered stages, each stage depending on the one before it, and an error is a stage executing on input the prior stage has not yet supplied. Sorting the ways the four-stage dependency can break yields five distinct error types plus one combination the dependency makes impossible. The five types are exhaustive (every error that breaks the dependency is one of the five) and the same five types appear in any field whose process proceeds through the four ordered stages. The five error types name which stage executed on undelivered input. Stage-2-on-stage-1 (Type 2-1): the contextualizing stage executes before the recognition stage has delivered, so it situates content whose existence is not yet established. Stage-3-on-stage-2 (Type 3-2): the resolving stage executes before the contextualizing stage has delivered, so it settles a state with no context to settle it against. Stage-4-on-stage-3 (Type 4-3): the committing stage executes before the resolving stage has delivered, so it carries forward a state with no resolved value. Stage-3-on-stage-1 (Type 3-1): the resolving stage executes on content admitted directly, bypassing the contextualizing stage, and settles a state that refers to nothing the admission supplied. Stage-4-on-stage-1 (Type 4-1): the committing stage executes when none of the prior stages has delivered, the whole sequence having failed to execute. This is the maximal failure, and it contains Types 2-1, 3-2, and 4-3 within it. The impossible combination is stage-4-before-stage-2 (Type 4-2): the dependency provides no route from the contextualizing stage to the committing stage except through the resolving stage, so there is no such step to fail, and the cell stays empty. The typology stakes six predictions. Exhaustiveness: every error that breaks the four-stage dependency, in any field, is one of the five types. Entailment: the maximal failure (Type 4-1) always co-occurs with its three interior failures (Types 2-1, 3-2, 4-3), while the direct-admission failure (Type 3-1) does not drag in the context-related failures it bypasses. Step-count gradient: on the same input in the same field, the maximal failure's consequences contain the consequences of each interior failure it is built from. Stage-1 fixity: no error pushes the first stage later within a single pass, because the first stage has no earlier stage to be ordered behind. Three-stage subset: a process missing one of the four stages exhibits only the error types that do not involve the missing stage, never the full five. Cross-field identity: errors sorted into the same type share the same operational signature whatever the field's content. Beyond the six predictions, the typology forbids a sixth error type as a structural constraint, not as a staked prediction: the count is fixed by which steps the dependency provides, not by free combination of stage pairs. The three core failures are the three adjacent-stage swaps. The two further types (the direct-admission failure and the maximal whole-sequence failure) follow from the longer-range steps the dependency admits. The derivation of the four-stage ordering, its longer-range steps, and the empty stage-4-before-stage-2 cell is carried in Stewart (2026e, 2026f, 2026g) and inherited here. The typology is the spine of a research program whose subsequent papers map each field's existing error catalog onto the five types. This paper names each type, defines each by which stage executed on undelivered input, fixes the entailment relations among them, and supplies the vocabulary the program's downstream papers reuse. **Keywords:** error analysis, error taxonomy, failure mode analysis, taxonomy of errors, diagnostic error, cognitive error, cognitive bias, heuristics and biases, judgment and decision making, error classification
