Ultrastability

Summary

Ashby models a system that changes its parameters when its existing dynamics cross critical conditions.

Implications for practice

Ask when changing the response rule becomes necessary, and what constrains that change.

Key distinctions

[]

Historical development

[]

Ideas it depends on

[]

Further developments

[]

Connections to practice

[]

Common confusions

[]

Further checks

• Extend the evidence pass beyond the cited passages.

Recorded connections

Check the wording, direction, scope, sources, and status of a connection before relying on it.

• Design for a Brain presents an account of Ultrastability

  Status: candidate · Relation: presents account of

  Limited to the identified passage. A practice analogy needs its own assumptions and evidence.

  Locator: Chapter 8, sections 8/4–8/7

  • Design for a Brain — 1954 corrected reprint of the 1952 edition (passage checked)

• Ultrastability uses critical limits on Essential variables

  Status: candidate · Relation: formalises

  Read in the context of Ashby’s particular model.

  Locator: Sections 3/14 and 8/4–8/7

  • Design for a Brain — 1954 corrected reprint of the 1952 edition (passage checked)

• Ultrastability models a mechanism for Adaptation

  Status: candidate · Relation: presents account of

  A proposed mechanism, not an assertion that all adaptation is ultrastable.

  Locator: Preface and chapter 8

  • Design for a Brain — 1954 corrected reprint of the 1952 edition (passage checked)

• Ashby: selection, regulation, and variety (Challoner, 2026) presents account of Ultrastability

  Status: candidate · Relation: presents account of

  In Challoner’s reconstruction: Ultrastability changes parameters when essential variables leave their limits.

  Locator: p. 4, DS3; p. 5, PS4

  • Ashby: selection, regulation, and variety: researcher module (source scoped research pass)

• Ultrastability specialises Regulation

  Status: candidate · Relation: specialises

  Source-scoped reading of Challoner’s module: Ultrastability adds parameter change when essential variables leave acceptable limits.

  Locator: p. 4, DS3; p. 5, PS4

  • Ashby: selection, regulation, and variety: researcher module (source scoped research pass)

Claims and disputes

• In Challoner’s reconstruction: Ultrastability changes parameters when essential variables leave their limits.

  Claim status: candidate. Review status: research pass needs editor.

  Source-scoped interpretation. Human editorial acceptance remains pending.

  Supporting sources

  • Ashby: selection, regulation, and variety: researcher module (source scoped research pass)

• Source-scoped reading of Challoner’s module: Ultrastability adds parameter change when essential variables leave acceptable limits.

  Claim status: candidate. Review status: research pass needs editor.

  Source-scoped interpretation. Human editorial acceptance remains pending.

  Supporting sources

  • Ashby: selection, regulation, and variety: researcher module (source scoped research pass)

Sources and passage locators

• Design for a Brain — 1954 corrected reprint of the 1952 edition (passage checked)
• Ashby: selection, regulation, and variety: researcher module (source scoped research pass)

• Ashby: selection, regulation, and variety: researcher module: p. 4, DS3; p. 5, PS4 · research pass needs editor
• Ashby: selection, regulation, and variety: researcher module: p. 4, DS3; p. 5, PS4 · research pass needs editor

Cite this entry

Taylor, B. P. (2026). Ultrastability. The Necessary Tangle, release 0.35. https://transduction.systems/entries/concept_ultrastability/

Include the release and review status when you quote or reuse this account.