*Fallibility as the signature.* Reasoning is distinguished from registration and feeling by being fallible. The conclusion can be invalid; the inference can miss; the being can arrive somewhere the medium does not require. Any account must explain why reasoning, alone among the chapter's registers, *can* be wrong in a structural sense, and what its being wrong consists in. The structural requirement is that the account locate reasoning's fallibility in the activity's commerce with the medium's constraints: the conclusion is hostage to what the medium permits, so the following-out can fail if it does not follow what the medium itself requires.

*Answerability to the structure.* Reasoning is the being's operation on the medium's structure: inferring what follows, projecting what is likely, weighing the possibilities the structure opens. Each such move answers to that structure: it is correct or incorrect according to whether it tracks what the structure permits or entails. Necessity is the limiting case, where the structure forces a single conclusion and the inference, correctly followed, is no longer optional; but the same answerability governs the moves the structure leaves open, where a projected likelihood is still right or wrong against the structure without being forced by it. Any account must explain this answerability — the validity in virtue of which a move can be mistaken — rather than treating valid inference as a contingent psychological habit. The structural requirement is that the account derive that standard from the medium's structure (T, S, Φ, and what they support) rather than from a transcendental architecture overlaying experience or from a formal pattern hovering independent of anyone. And it must locate the answerability in the right place: where knowledge answers to the structure as a map answers to what it maps, reasoning answers as an operation does, by whether the move it makes follows what the structure licenses.

*Internal standard.* Reasoning's standard is internal to its activity: the activity is the medium's constraints being followed out, and what is followed out is what is forced. Any account must explain why reasoning has a standard at all, and why the standard is not externally imposed. The structural requirement is that the account treat reasoning as constituted by its answerability to the structure it operates on — the standard is what reasoning *is*, not a separate norm applied to it from outside.

*Recursion on the being's own holdings.* Reasoning is the recursion taking its own holdings as the thing being operated on: testing what it has held against what it is now registering, following the medium's constraints from the test to wherever they lead. Any account must distinguish reasoning from registration without making it a separate faculty. The structural requirement is that the account derive reasoning from the same recursive activity that constitutes registration, at the depth where the recursion has folded back far enough to operate on what it has previously taken in.

*Continuity with affect and registration.* Reasoning operates on what affect and registration deliver, and the underlying registrations remain active beneath the reasoning. Any account must explain this continuity rather than treating reasoning as autonomous from the layers below. The structural requirement is that the account locate reasoning at the depth where the operation-on-holdings becomes available, with the underlying layers continuing to supply what the reasoning operates on.

*Inventory of operations.* Reasoning runs in several distinct forms: deduction following the medium's constraints out to what they entail; induction inferring patterns from particulars; abduction inferring the best explanation of what has been registered; reflective examination of one's own model. Any account must accommodate the inventory rather than reducing reasoning to any single operation. The structural requirement is that the account treat the inventory as different operations the same recursion can run, each answerable to the medium's structure in its own way.

*Depth-graded distribution.* Reasoning runs at depths well below the metacognitive turn: transitive inference, means-end planning, tool manufacture, deception. Reasoning about reasoning (metacognition) requires the self-aware level [§8.1](<8.1 Drive.md>) names. Any account must accommodate the gradient rather than restricting reasoning to the human case or to the metacognitively self-aware. The structural requirement is that the account distinguish what runs at each depth and identify the threshold at which metacognition becomes available.

*Substrate-independence at the structural level.* As with consciousness and awareness, the recursive activity that constitutes reasoning can in principle be realized in different substrates. Any account that ties reasoning essentially to biological substrates must argue for why the structural activity could not be realized elsewhere. The structural requirement is that the account distinguish substrate independence at the structural level (the same recursive activity can run in different media) from substrate-specific content (what the activity operates on depends on what is doing the operating).

*Coherence with the rest of the chapter.* Reasoning, knowledge ([§8.3](<8.3 Knowledge.md>)), meaning ([§8.8](<8.8 Meaning.md>)), and language ([§8.10](<8.10 Language.md>)) are structurally connected: reasoning produces knowledge, knowledge stabilizes meaning, language transmits both. Any account must accommodate these connections rather than treating reasoning in isolation. The structural requirement is that the account make reasoning's products available to the registers downstream of it, with the depth at which reasoning operates conditioning what those registers can hold.

Taken together these requirements set out the explanatory program the framework [§8.4](<8.4 Reasoning.md>) defends: fallibility, answerability, internal standards, recursion on prior holdings, continuity with affect and registration, multiple operations, depth-graded distribution, substrate questions, and links to other registers. They are not neutral constraints on every account of reasoning. The framework argues for this integrated picture rather than treating its claims about recursion, cross-species reasoning, or substrate independence as established by cognitive science alone.


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← [8.4.1 What is Disputed](<8.4.1 What is Disputed.md>) | [8.4.3 What is Predicted](<8.4.3 What is Predicted.md>) →
