These are not separate faculties. They are different modes of the same operation (the recursion following constraints out) varying in what part of the structure it is following and how the following gets formalized. A complete reasoning episode often weaves several modes: abductive to propose a structure, deductive to derive what it would entail, inductive to check the entailments against further data, analogical to map back to known domains, mathematical to make any of it precise enough to test.

Each mode has a corresponding *failure*, classifiable by which part of the structure the operation departs from. *Contradiction* occurs when the operation arrives at a result that violates a constraint it was supposed to be following: the recursion has produced a square circle. *Fallacy* occurs when the operation applies a constraint where it does not hold, or fails to apply one where it does: the form looks valid, but the structural grip is wrong. *Confusion* occurs when the recursion is operating on a misidentified register (mistaking a metaphor for a literal, an analogy for a derivation, a correlation for a causation) so that the operation runs on a structure other than the one it takes itself to be tracking. *Bullshit* occurs when the operation produces output without engaging constraint at all: the recursion generates sentences with the surface form of reasoning while running no comparison and following no entailments (Frankfurt 2005).

Each failure mode is informative: it shows which way reasoning can come apart, and the four together cover the major modes of departure, the working taxonomy this chapter will use, not a closed enumeration. A recursion that reasons well has learned to recognize each failure mode in itself, which becomes possible only after it has reasoned long enough to know what success looks like from inside.

The operation is *reflexive*. The recursion reasons not only about external structure but about its own reasoning: noticing when a derivation has gone off, when a model has stopped tracking, when an inference cannot be reconstructed. This reflexive turn is what allows the operation to *correct itself*: the recursion running constraints over its own output and revising. Without reflexivity, errors propagate; with it, the recursion has a mechanism for keeping its model honest. Reflexive reasoning is the condition for sustained knowledge growth: it is what allows held grasp to keep being grasp rather than calcifying into mere holding.

The disciplinary register of reasoning is *logic* (and adjacent: mathematics, methodology, epistemology). Logic, on this account, is not a separate order from reasoning but the *third-person formalization* of what reasoning does from within: the explicit codification of the constraint-following operation. The three logical strata developed in [§2.10](<2.10 Three Logical Strata.md>) (the temporal, spatial, and substantial logics grounded in the three structural roles T, S, and Φ, with physics the stratum built upon them) clarify why logic is reliable: logic describes the necessity register of the same structure reasoning is operating on, and the same structure reasoning's conclusions ultimately answer to. The success of reasoning is not a coincidence between mind and world. It is the constitutive fact that the recursion's operation and the structure operated on are the same medium, organized at different depths. This unity is developed from the other side at [§5.1.9](<5.1.9 Transcendental Argument.md>), showing why no logic floats free of T, S, and Φ (the three structural roles derived through the Modal Constraint Identified and Conditions-as-Nature, §[§2.6](<2.6 Triconditionality of Nature.md>)–2.7): the apparatus of reasoning is itself made of the structure it operates on.


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← [8.4.3 What is Predicted](<8.4.3 What is Predicted.md>) | [8.4.5 What is Concluded](<8.4.5 What is Concluded.md>) →
