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πŸ”­ Methodeutics

The logic of inquiry. Statistics formalizes induction: how to generalize from observations. Methodeutics formalizes abduction: how to generate the next question. Peirce named both the mode (1878) and the field (1902). This is the textbook.

Modes of reasoning

Mode Edge Field Status
DeductionTheory β†’ ExperimentLogic, mathematicsFormalized (Aristotle β†’ Frege β†’ GΓΆdel)
InductionExperiment β†’ ObservationStatisticsFormalized (Fisher β†’ Neyman β†’ Ramdas)
AbductionObservation β†’ TheoryMethodeuticsThis textbook

Everyone does abduction. Doctors call it diagnosis. Engineers call it debugging. Detectives call it deduction (wrong, but Doyle didn't read Peirce). The pieces have always existed: philosophy, cognitive science, program analysis, causal inference, sequential testing.

between vision and root
blooms branches and shoots

prune the duds
thence more buds

clues for felling
perfuse its telling

do trees need an arbor
in light, soil and water?

Chapters

Each chapter opens with a system that breaks under the previous chapter's tools. The breakage motivates the new concept. The textbook's structure embodies the method it teaches: the shape of the failure names the next chapter.

Part I: The trichotomy

Chapter
1. Three modes Holmes and the dog that didn't bark. Doyle called it deduction. It isn't. πŸ”­
2. Security and uberty Popper says discovery has no logic. Peirce says it does, but admits it's insecure. πŸ”­
3. Eight names, one operation Bi-abduction, figure-ground, equilibration, intervention. Six fields, zero cross-citation. πŸ”­

Part II: The primitive

Chapter
4. Diff A mechanic taps the alternator. The engine stalls. Two hypotheses fire. Where did they come from? πŸ”­
5. Bi-abduction Infer runs on millions of lines. It infers the frame automatically. But bi-abduction is one path. πŸ”­
6. Tri-abduction The program branches. Each branch changes different state. Bi-abduction can't handle the fork. πŸ”­
7. Economy of research Ten hypotheses, budget for three experiments. Which three? πŸ”­

Part III: The evidence

Chapter
8. Evidence has a trajectory An A/B test says B is better. You ship. Six months later, B is worse. The snapshot lied. πŸ”­
9. Four bins The trajectory oscillates. Is the system fighting itself, or is your measurement noisy? πŸ”­
10. The hypothesis graph A monotone trend test fires but curvature is indeterminate. The failure mode is the next hypothesis. πŸ”­
11. Convergence Five sensor streams, each individually undetectable. Composed e-values classify the forcing pattern. πŸ”­

Part IV: The machine

Chapter
12. Protecting the loop An agent confirms every hypothesis. It abduced from the data and tested on the same data. πŸ”­
13. Validators Four validator types, one interface. Empirical, structural, proof, counterexample. πŸ”­
14. The pipeline Three witnesses (Infer, Voyager, IRM), each closing the loop in a different domain. None cite each other. πŸ”­
15. Case study A system that searches without reasoning. It can perturb and observe but never asks why. πŸ”­

Appendix: Primary Sources

Appendix
A. Deduction, Induction, and Hypothesis The bean syllogism. The 1878 origin of the trichotomy (Ch 1). πŸ”­
B. A Neglected Argument Musement and the three stages of inquiry. Foundations for Ch 2. πŸ”­

Peirce's vocabulary

Terms coined or repurposed by Charles Sanders Peirce (1839–1914) that do work in this textbook.

Term Meaning
AbductionInference from a surprising fact to an explanatory hypothesis. The only mode that introduces new ideas.
RetroductionSynonym. Leading backward, from effect to cause.
MethodeuticThe third branch of logic: the study of methods of inquiry. (After speculative grammar and critical logic.)
UbertyThe productive richness of a reasoning mode. Abduction: highest. Deduction: lowest. From Latin ubertas (fruitfulness).
SecurityThe certainty of a reasoning mode. Inverse of uberty. Deduction: highest. Abduction: lowest.
Economy of researchHypothesis selection guided by cost-benefit: which experiment gives the most information per dollar?
MusementFree, purposeless contemplation: "antipodal to vacancy and dreaminess." The pre-logical state from which abductive hypotheses emerge.
PragmaticismThe meaning of a concept is its conceivable practical effects. Renamed from pragmatism: "ugly enough to be safe from kidnappers."

Status

All 15 chapters drafted and copyedited. Codex-reviewed to convergence.

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