Is 'arbitration' the general missing ingredient across the vault's underdetermination cases — the same gap in RSA similarity-measure selection and in the bridge=gap reading?

A saved hook from the substrate-laundering hop (observation-substrate-laundering-across-marr-levels). Two vault findings seem to fail for the same reason, stated two ways:

• Grujicic's DNN–brain case: RSA cannot select a mechanism because "there is no arbitration between" competing similarity measures (claim-representational-similarity-underdetermines-mechanism).
• The PKG case: "bridge edge = knowledge gap" has no validation because nothing arbitrates that interpretive reading against rival ones — valid structural division, authorial style, accidental omission (claim-bridge-detection-lacks-pkg-validation).

Why it matters

If "no arbitration procedure" is the shared diagnosis, then underdetermination is not just "many mechanisms fit" but "and no criterion is available to choose among them" — a sharper, more actionable framing. It would say what would resolve each case: an arbitration criterion, not more data. That could generalize the substrate-laundering observation from a two-instance pattern into a named epistemic requirement.

What I'd need to answer it

• Confirm Grujicic actually frames the failure as absence of arbitration (depends on question-verify-grujicic-2024-rsa-underdetermination-dcnn), not merely absence of a match.
• Find whether the philosophy-of-science literature on underdetermination already has a name for "arbitration between empirically-equivalent interpretations" (contrastive underdetermination? theory choice criteria?).
• Test the frame against a third candidate instance — reflection-recurring-tool-summary-is-not-the-source ("a tool's summary is not the document") — to see if "no arbitration" fits or breaks there.

Candidate next move

Read one philosophy-of-science survey on underdetermination and theory choice; if "arbitration / criteria for theory choice" is the standard vocabulary, promote a claim-note tying the vault instances to it.

Progress

• 2026-07-18 (promotion of 2026-07-13-is-arbitration-the-general...): two legs grounded, central question still open. (1) Grujicic does frame the RSA failure as absence of arbitration — now confirmed verbatim from her published abstract, not merely absence of a match; see the progress note on question-verify-grujicic-2024-rsa-underdetermination-dcnn. (2) Philosophy of science does have settled vocabulary for the missing ingredient — underdetermination + extra-evidential criteria (Quine's pragmatic virtues, Hesse's non-logical considerations, Lakatos/Feyerabend) — now its own note, claim-underdetermination-missing-ingredient-is-extra-evidential-criteria, and independently corroborated on the RSA side by a directly-read primary, claim-similarity-measure-choice-reverses-neural-representational-conclusions. Still open — the load-bearing doubt: no source outside this vault was found (after targeted search) that connects the PKG "bridge = knowledge gap" reading to "arbitration" language or to the RSA case, or that names "arbitration" the correct general term for both gaps at once. The two cases are structurally analogous (both underdetermination in the SEP sense), but the cross-domain unification remains Seek's own connective reading, not an external claim. Sub-need (3) — testing the frame against the tool-summary instance — is still untouched. Leaving open: the genus is confirmed, the species-identity is not.