Defending Bayes, Part 8

Series: Defending Bayes (Part 8)

Summary

Addresses critical rationalist (Deutsch-Hall) critique of Bayesian reasoning by distinguishing abduction from induction and clarifying when Bayesian reasoning applies.

Key Concepts:

Crit-Rat Critique:

• Deutsch-Hall position: Reject induction as logically invalid; knowledge is conjectural, never inductively justified
• Abduction vs induction: Abduction (inference to best explanation) doesn’t claim incremental certainty, only provisional selection
• Objection to Bayesianism: Assigning prior probabilities to theories seems arbitrary; numerical credences imply incremental justification

Resolution:

• Scientific theories aren’t binary: Theories are contextually/approximately true within domains (e.g., Newtonian mechanics)
• Credences reflect epistemic uncertainty: Rational credences represent uncertainty about scope/accuracy/limitations, not absolute truth
• Deutsch-Hall’s error: Conflating objective truth (contextual approximations) with subjective uncertainty (credences)

Proper Boundary:

• Accept Bayesian reasoning for subjective uncertainty within objective theoretical structures (like QBU)
• Reject naive application that assigns intrinsic probabilities to theories themselves

Tags

• epistemology
• bayesian
• critical-rationalism
• philosophy-of-science
• deutsch
• abduction
• induction
• sequence

Cross-References

• Backward: Defending Bayes, Part 7
• Forward: Defending Bayes, Part 9 (Interlude)
• Related: Earlier “Defending Bayes” posts (Parts 1-7)
• Related: QBU framework posts
• Related: Defending Bayes, Part 9 (Interlude)
• Related: Karl Popper (falsificationism)

Notes

• Part of extended Defending Bayes sequence
• Engages seriously with critical rationalist objections
• Demonstrates willingness to refine position in response to critiques
• Published June 5, 2025—extremely productive day (multiple substantial posts)
• Shows intellectual engagement with “crit rat” community