*Three irreducible forms.* Knowledge comes in at least three genuinely distinct forms: propositional (knowing-that), procedural (knowing-how), and acquaintance (knowing what it is like from inside). Any account must accommodate all three or supply an argument for reducing some to others. The structural requirement is that the account explain why these three forms are distinct genuine modes of holding structure rather than treating one as fundamental and the others as derivative.

*Held grasp of structure.* What unifies the three forms is what they hold: structure, the way the medium actually is. Whether held as model, as encoding, or as direct subjective character, the target is the same. Any account must locate knowledge at the relation between a being's grasp and the structure of what is the case, rather than at the relation between a believer and a proposition with truth as an external constraint. The structural requirement is that the account treat truth as constitutive of strong-sense knowledge (held grasp answering to what is the case) rather than as an additional condition on a separately-specified belief.

*Strong and ordinary senses distinguished.* Strong-sense knowledge (held grasp of structure as it actually is) fails as knowledge when the grasp does not fit. Ordinary fallible empirical knowledge is partial, approximate, revisable, and counts as knowledge by tracking the structure well enough to do the work the being uses it for. Any account must distinguish the two senses without collapsing one into the other. The structural requirement is that the account treat strong-sense knowledge as the analytic core and ordinary knowledge as the working-resolution form, with the post-Gettier debates as the local literature on the propositional form's behavior at the working resolution.

*Gettier-vulnerability located at the propositional form.* The Gettier counterexamples target the JTB analysis of propositional knowledge specifically. Procedural knowing-how and acquaintance are not vulnerable to Gettier-style counterexamples in the same way. Any account must locate Gettier-vulnerability at the propositional form's specific structure rather than treating it as a problem for knowledge as such. The structural requirement is that the account explain *why* the propositional form generates Gettier cases and the other forms do not.

*Connection to reasoning.* Knowledge is what reasoning ([§8.4](<8.4 Reasoning.md>)) produces and extends. Held grasp does not extend itself; the being must operate on what it holds for the holding to deepen. Any account must connect knowledge to reasoning rather than treating epistemology as autonomous from the activity that builds knowledge. The structural requirement is that the account derive the formation and growth of knowledge from the operations [§8.4](<8.4 Reasoning.md>) names: deduction, induction, abduction, reflective examination.

*Connection to meaning.* Knowledge concerns whether the model fits; meaning ([§8.8](<8.8 Meaning.md>)) concerns where the model is heading. Any account must distinguish accuracy-tracking (knowledge) from direction-tracking (meaning) while explaining their relation. The structural requirement is that the account preserve the bridge: meaning operates on the same model knowledge stabilizes, with the two registers picking up different structural features of the same orientation.

*Depth-graded distribution.* Knowledge runs at depths well below the propositional. Procedural knowing-how is widespread across the animal kingdom; spatial and ecological knowledge organizes much of vertebrate life; acquaintance obtains wherever a vantage opens at all. Propositional knowledge in the strong sense requires the recursive depth at which the being can hold a belief-shaped representation answering to a fact. Any account must accommodate the gradient rather than restricting knowledge to the propositional human case. The structural requirement is that the account distinguish what runs at each depth and identify the depth required for each form.

*Substrate-independence at the structural level.* As with the other registers, the activity of holding structure can in principle be realized in different substrates. Any account that ties knowledge 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 from substrate-specific content.

*Coherence with skeptical scenarios without surrender to them.* Constructed skeptical scenarios produce conditions under which knowledge would systematically fail; ordinary practice produces knowledge under conditions that actually obtain. Any account must explain why skeptical scenarios do not undermine ordinary knowledge claims while still acknowledging what the scenarios get right. The structural requirement is that the account treat strong-sense knowledge as fit-dependent (and therefore failing in constructed mismatch scenarios) while preserving ordinary knowledge as the working resolution at which the fit holds.

These requirements name the explanatory program the framework [§8.3](<8.3 Knowledge.md>) defends: three forms of knowledge, a relation between grasp and world, strong and ordinary senses, a proposed account of Gettier vulnerability, links to reasoning and meaning, depth-graded distribution, substrate questions, and skeptical scenarios. They are not neutral constraints accepted across epistemology. In particular, whether the three forms are irreducible, whether acquaintance obtains across lineages, and whether knowledge is substrate independent remain contested. The framework argues for this package rather than treating it as established.


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← [8.3.1 What is Disputed](<8.3.1 What is Disputed.md>) | [8.3.3 What is Predicted](<8.3.3 What is Predicted.md>) →
