Moral Geometry: Endogenous Scaling in Nash-Kantian Games
Pith reviewed 2026-06-26 11:08 UTC · model grok-4.3
The pith
By publicly choosing a scale, a Kantian player can implement the Stackelberg leader outcome under strategic complements and earn more than the Nash payoff.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
The Kantian player can characterize stationary outcomes implementable by a common monotone scale. A sharp dichotomy emerges: under strategic substitutes scaling is defensive and the Kantian approaches but cannot exceed player 2's Nash benchmark; under strategic complements scaling is offensive and the Kantian can stationary-implement the Stackelberg leader outcome and obtain a payoff strictly above the Nash benchmark. In Cournot and differentiated Bertrand examples the scales are explicitly constructed and verified as local transformed Nash-Kantian equilibria.
What carries the argument
The publicly chosen smooth increasing scale, which alters the Kantian first-order condition through endogenous elasticity weights and serves as a commitment device.
If this is right
- The Kantian player obtains a payoff strictly above the Nash benchmark under strategic complements.
- Under strategic substitutes the Kantian eliminates the payoff loss from naive behavior but stays at or below the Nash benchmark.
- Allowing player-specific scales aligns the Kantian condition with the full Stackelberg reaction curve under complements but violates monotonicity under substitutes.
- Endogenous scaling acts as a commitment mechanism connecting Kantian optimization to strategic leadership.
Where Pith is reading between the lines
- Moral agents in repeated interactions might select representations of actions to gain strategic advantages.
- The trade-off between universality and strategic flexibility could appear in other equilibrium refinements that depend on how actions are measured.
- Experimental tests could ask subjects to choose scales in simple games and observe whether they select ones that implement desired outcomes.
Load-bearing premise
There exists a smooth increasing scale whose local elasticity ratios make the Kantian first-order condition coincide with the Stackelberg condition while preserving monotonicity and satisfying second-order conditions.
What would settle it
A counterexample in a strategic complements game where no monotone scale satisfies the required local elasticity ratios for the Kantian first-order condition to match the Stackelberg outcome.
read the original abstract
We study the strategic implications of the non-invariance of multiplicative Kantian equilibrium (MKE) under monotone transformations of the strategy space. Before interacting with a standard Nash player, a Kantian player publicly selects a smooth increasing scale that determines how proportional deviations are evaluated. Material payoffs and feasible actions remain unchanged, but the chosen scale alters the Kantian first-order condition through endogenous elasticity weights. The representation of actions therefore becomes a commitment device. We characterize the stationary outcomes implementable by a common monotone scale. A sharp dichotomy emerges. Under strategic substitutes, the Kantian player can approach the Nash payoff arbitrarily closely but cannot exceed player 2's Nash benchmark; scaling is defensive and eliminates the payoff loss associated with naive Kantian behavior. Under strategic complements, scaling becomes offensive: the Kantian player can stationary-implement the Stackelberg leader outcome and obtain a payoff strictly above the Nash benchmark. In the canonical Cournot and differentiated Bertrand examples, we explicitly construct scales satisfying the required local elasticity ratios and verify the second-order conditions, so the stationary outcomes are local transformed Nash-Kantian equilibria. Allowing player-specific scales would align the Kantian first-order condition with the Stackelberg condition along the entire reaction curve under complements, but would violate monotonicity under substitutes. This reveals a trade-off between universality and strategic flexibility. The results identify endogenous scaling as a commitment mechanism and connect Kantian optimization to strategic leadership and strategic non-equivalence.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript investigates how a Kantian player can use a publicly chosen smooth increasing scale on the strategy space to modify the multiplicative Kantian equilibrium when facing a standard Nash player. The scale acts as a commitment device by altering the Kantian first-order condition through endogenous elasticity weights, without changing material payoffs. The paper characterizes the stationary outcomes that can be implemented with a common monotone scale, identifying a dichotomy based on strategic substitutes versus complements. Under substitutes, defensive scaling allows the Kantian to approach the Nash payoff but not exceed it. Under complements, offensive scaling enables implementation of the Stackelberg leader outcome with a strictly higher payoff. Explicit constructions of such scales are provided for the Cournot and differentiated Bertrand games, with verification of the second-order conditions ensuring local equilibria.
Significance. This paper offers a novel perspective on Kantian optimization by framing endogenous scaling as a strategic commitment tool, linking it to concepts like Stackelberg leadership. The provision of explicit scale constructions in canonical examples and the verification of local equilibrium conditions strengthen the practical applicability of the theoretical results. The analysis of common versus player-specific scales reveals an interesting trade-off between universality and flexibility, contributing to the understanding of non-equivalence in strategic settings.
minor comments (2)
- The notation for the scale function, elasticity ratios, and transformed Nash-Kantian equilibrium could be introduced with greater clarity in the introduction and setup sections to aid readers.
- In the Cournot and Bertrand examples, a diagram showing the constructed scale function and its local elasticity adjustment would improve intuition for the constructions.
Simulated Author's Rebuttal
We thank the referee for their positive assessment of the manuscript, their accurate summary of the results on endogenous scaling as a commitment device, and their recommendation to accept. We are gratified that the dichotomy between strategic substitutes and complements, the explicit constructions in the Cournot and differentiated Bertrand examples, and the discussion of common versus player-specific scales were viewed as strengthening the contribution.
Circularity Check
No significant circularity identified
full rationale
The paper characterizes which stationary outcomes are implementable when a Kantian player publicly selects a smooth increasing scale function that reweights proportional deviations via local elasticities. The explicit constructions in the Cournot and differentiated Bertrand sections set those elasticities so the transformed Kantian first-order condition coincides with a target (Nash or Stackelberg) point while preserving monotonicity and satisfying second-order conditions. This is a direct demonstration that such functions exist and produce local equilibria; it does not derive an independent prediction that is then shown to equal its own inputs by construction. No self-citation chain, fitted-parameter prediction, or uniqueness theorem imported from prior work is invoked to force the result. The derivation therefore proceeds from the stated primitives (material payoffs unchanged, scale chosen publicly, monotonicity required) without circular reduction.
Axiom & Free-Parameter Ledger
free parameters (1)
- monotone scale function
axioms (2)
- domain assumption The scale is smooth and strictly increasing
- domain assumption Stationary outcomes are local transformed Nash-Kantian equilibria
Reference graph
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