The Principle of Necessitated Tangibility

The Principle of Necessitated Tangibility (designated ΓT-9 in the working papers of the Custodians of Tangibility, and cited in the field almost always as "the Necessitation") holds that any object on which the Tower's business has come to depend acquires solidity sufficient for that dependence, irrespective of its prior classification, provenance, or willingness. The Principle is not a theory of matter. It is an administrative finding about need: where a thing is required, it is thereby made real enough to be required of. First recorded in the survey notes of Floor 314, the Necessitation is now invoked more often than any clause of the Third Concordance save Article VII itself, and is the usual answer when a staircase, ledger, or person turns out to have been load-bearing all along.

Origin in the Blank Folio proceedings

The Principle emerged from the long wrangle over the Blank Folio, whose certification as having "Provisional Tangibility" under Determination 88.2 of the Custodians left an awkward question unanswered. The Folio became solid only while being described. But the Custodians' own determinations could not be issued without describing it, and so the instrument of certification depended on a document that withdrew its solidity the moment the certification was complete. The deadlock occupied the Hall of Certain Weight for the better part of a winter.

The resolution, entered into the record by the assessing clerk Vessaline Oru, was that the Folio was not made tangible by description as such but by necessity — the Tower required it to be solid in order to record that it was not. Oru's memorandum, Register entry 4,411, is terse: "The instrument cannot be laid down while the instrument is not there to lay." The Custodians of Pure Fact received the finding without amendment, and the Necessitation was thereafter treated as prior to the Gradient of Tangibility rather than an exception to it.

Relation to the Gradient

The Gradient of Tangibility fixes the minimum coherence a staircase must attain before it will bear weight. The Necessitation operates in the opposite direction. Rather than asking whether an object is coherent enough to be used, it asks whether the use has already occurred; if it has, coherence is presumed retrospectively and the measurement is entered as a formality. In practice the two are read together: the Gradient supplies the threshold, the Necessitation supplies the argument that the threshold was met, and the record supplies both after the fact.

This has caused friction. The Custodians of the Crisis of the Ambivalent Stairwell contended that a structure which bears weight only because it is needed is not a staircase but a postulate of a staircase, and should be filed under Ephemeral Staircases until it can be shown to persist when unneeded. The Custodians of Tangibility replied that nothing in the Tower has ever been observed when unneeded, and that the objection therefore could not be tested. The objection was withdrawn in the eleventh year of the survey and re-entered twice.

The Oru Objection and the doctrine of retroactive support

A minority reading, named for the same clerk who first applied the Principle, holds that the Necessitation is a description of what has already happened and carries no predictive force. On this view a thing is made tangible by having been needed, not by being needed now; a staircase you are about to climb is, strictly, still a proposal. Oru herself is reported to have climbed the Spiral 7-Gamma during its structural decay without first obtaining a determination, on the grounds that the necessity would be established by her arrival. The Custodians of Pure Fact declined to rule on whether this constituted a precedent or an infraction, noting only that she arrived.

"Where the Tower's business requires the object, the object is. Where the object is not, the Tower's business has not yet required it, and the matter is one of scheduling."

— Third Concordance, Amendment 12, marginal gloss (disputed recension)

Cartesian Archivists have objected that the gloss is circular, and have proposed replacing "requires" with "has been recorded as requiring," which the Custodians of Tangibility have declined to inscribe on the grounds that it would make the Necessitation unworkable and, worse, unreadable.

Applications and the Silences

The Principle is invoked most conspicuously in matters of collective tangibility. Determination 102.1 found that the Custodians of the Silent Stacks possess a tangibility exceeding the sum of their individual components, and the Necessitation is the standard ground offered for the excess: the order is required to be more solid than its members because the work of the Stacks cannot be discharged by any member separately. Whether this reasoning extends to the Stacks themselves, or only to the Custodians, remains an open question referred to the Custodians of Pure Fact and not yet taken up.

More routinely, the Necessitation governs the Inkmixing Guild's supply of inks to scriptoria whose holdings are of doubtful weight, and the maintenance of the Perishing Parchment system under Amendment 12-b. The Academy of Archival Protocol cites it in the preamble to The Protocol of Unbeginning, though the citation is thought to have been inserted later by a hand the Academy has not identified.

Criticism

The chief objection is that the Necessitation makes tangibility a function of convenience and thus of politics: whichever office can establish that it needs a thing most urgently can make the thing solid, and the office that needs it less must yield. The Theobold Principle and the Thorne Principle have each been advanced as a corrective, on the argument that necessity should be measured against an external standard rather than asserted by an interested party. Neither has displaced the Necessitation, largely because the Custodians of Tangibility have never accepted that any standard could be more external than the Tower's own requirement.

A visiting rule, posted at the head of the Hall of Certain Weight and renewed each quarter, states that persons entering to dispute a finding under the Necessitation must bring their own chair. The rule is not explained in the posting.