IESET.
Hypotheses·fiscal·fiscal_dominance_japan_debt_non_crisis

Japan post-1990 has run gross public-debt-to-GDP ratios from ~70% rising to ~250%, the highest sustained level in the OECD record, WITHOUT triggering inflation, currency collapse, sovereign-spread blowout, or fiscal-dominance-induced loss of monetary control.

This case is a counter-example to the Sargent-Wallace 1981 "unpleasant monetarist arithmetic" prediction that high debt-to-GDP under monetary independence forces eventual monetisation and inflation. The post-Keynesian / MMT reading is that for a sovereign currency issuer with deep domestic savings absorption, the debt-stock constraint is a political-economy constraint about real-resource allocation, not a market-discipline constraint about solvency. The hypothesis tests whether Japan's debt path 1990-2024 violates the Sargent-Wallace prediction at standard significance, and whether inflation, JGB yields, and JPY trade-weighted index remained within non-crisis bands across the period.

INCONCLUSIVEengine/runs/fiscal_dominance_japan_debt_non_crisis

INCONCLUSIVE_PENDING_DATA

confidence cueResult card produced; verdict unclassified.

policy briefCoverage too thin

In ordinary language

In plain terms, this asks whether the policy story survives a real-world data check from 1990 to 2024.

plain answer

This test cannot make a firm call yet. INCONCLUSIVE_PENDING_DATA

why it matters

This matters because fiscal claims should change belief only when they survive a pre-declared empirical test.

how the test works

It compares 1 country or place units from 1990 to 2024, using a multi metric checklist design.

what was measured
What we checked
  • Gross general government debt income
  • Cpi inflation yoy
  • Jgb 10y yield
what this does not prove

A single test is not the whole truth. It narrows the claim under a specific sample, time period, and method. Strong policy conclusions need the pattern to survive nearby tests, alternative data, and serious objections.

verification

No evidence packet has been generated yet.

Results

engine/runs/fiscal_dominance_japan_debt_non_crisis
1007550250199020072024JPN
illustrative sketch · run pending
No coefficients yet. When the model fires, this chart will show gross_general_government_debt_gdp across 1 sampled countries over 1990–2024.
The shapes above are stylised — none of the lines are real data.
Placeholder for fiscal_dominance_japan_debt_non_crisis. Published chart will be generated from engine/runs/fiscal_dominance_japan_debt_non_crisis/chart_data.json.

Pre-registration

pre-registered
first-spec commit 098ce96 · 2026-04-30T12:57:33Z
run generated · 2026-05-01T08:58:03Z

Japan post-1990 has run gross public-debt-to-GDP ratios from ~70% rising to ~250%, the highest sustained level in the OECD record, WITHOUT triggering inflation, currency collapse, sovereign-spread blowout, or fiscal-dominance-induced loss of monetary control. This case is a counter-example to the Sargent-Wallace 1981 "unpleasant monetarist arithmetic" prediction that high debt-to-GDP under monetary independence forces eventual monetisation and inflation. The post-Keynesian / MMT reading is that for a sovereign currency issuer with deep domestic savings absorption, the debt-stock constraint is a political-economy constraint about real-resource allocation, not a market-discipline constraint about solvency. The hypothesis tests whether Japan's debt path 1990-2024 violates the Sargent-Wallace prediction at standard significance, and whether inflation, JGB yields, and JPY trade-weighted index remained within non-crisis bands across the period.

Falsification criterion — what would disprove this

set before the run · honoured after

This hypothesis is considered falsified if:

Evaluate every canonical_metrics row against its pre-registered source, window, and threshold. The hypothesis is SUPPORTED if at least 4 of 5 metrics are MET. It is REFUTED if even counting all pending metrics as favorable cannot reach 4 MET metrics and the confirmed failures cross the pre-registered refutation guardrail. Otherwise the verdict is INCONCLUSIVE until pending data or pending evaluation metrics are resolved.

formal test & threshold
test:      multi_metric_checklist_canonical_case
threshold: MET >= 4 of 5; REFUTE when MET + PENDING_DATA + PENDING_EVAL < 4; refutation guardrail=2

Method

Template
multi_metric_checklist
Clustering
none
Sample
1 countries · 1990 – 2024
Evidence type
canonical_case_multi_metric

Canonical-case checklist evaluator reads canonical_metrics and multi_metric_falsification; no regression model is estimated. Each metric is scored against its pre-registered source, window, and threshold before applying the count rule below.

Data

VariableSourceTransform
gross_general_government_debt_gdp
outcome
imf:WEO_GGXWDG_NGDPtier 2
level
cpi_inflation_yoy
outcome
fred:JPNCPIALLMINMEItier 1
yoy
jgb_10y_yield
outcome
oecd:OECD.SDD.STEStier 2
level
jpy_real_effective_exchange_rate
outcome
bis:WS_EERtier 2
level

● ready  · ● pending  · ● reconstruct-needed

Detailed result card

Result card — fiscal_dominance_japan_debt_non_crisis

Verdict: inconclusive (data gaps)

Reason: 3 metrics met, 2 pending; 1 more need resolution

Pre-registered rule: SUPPORT if >= 4 of 5 metrics met; REFUTE if <= 2 met (impossible to hit support).

Counts: 3 MET · 0 NOT_MET · 2 PENDING_DATA · 0 PENDING_EVAL

Primary country: JPN

Metric-by-metric

| # | Metric | Status | Observed | Threshold | Notes | |---|---|:---:|---:|---|---| | 1 | debt_to_gdp_threshold_breach | MET | 179 (2010) [min_level_in_window] | >150% sustained 2010-2024 | min_level_in_window = 178.600; threshold >150 | | 2 | cpi_inflation_below_persistent_threshold | MET | 3.27 (1991) [max_yoy_pct_change_in_window] | <4% persistent across 1990-2024 (max ~3% transient post-COVID) | max_yoy_pct_change_in_window = 3.273; threshold <4 | | 3 | jgb_10y_yield_below_crisis_band | PENDING_DATA | | <5% across 1990-2024 (max ~1.5% in early 1990s, peaked ~1.7% in 2025) | No usable vintage for: oecd:OECD.SDD.STES,DSD_KEI@DF_KEI,4.0 | | 4 | jpy_trade_weighted_index_no_collapse | MET | 41.7 (1990) [peak_to_trough_pct_decline] | no >50% REER decline in any 12-month window 1990-2024 | | | 5 | monetary_policy_independence_preserved | PENDING_DATA | | BoJ retains operational policy autonomy across 1990-2024 per qualitative coding | No usable vintage for: boj:policy_governance_record, academic:bof_independence_index |

Claim

Japan post-1990 has run gross public-debt-to-GDP ratios from ~70% rising to ~250%, the highest sustained level in the OECD record, WITHOUT triggering inflation, currency collapse, sovereign-spread blowout, or fiscal-dominance-induced loss of monetary control. This case is a counter-example to the Sargent-Wallace 1981 "unpleasant monetarist arithmetic" prediction that high debt-to-GDP under monetary independence forces eventual monetisation and inflation. The post-Keynesian / MMT reading is that for a sovereign currency issuer with deep domestic savings absorption, the debt-stock constraint is a political-economy constraint about real-resource allocation, not a market-discipline constraint about solvency. The hypothesis tests whether Japan's debt path 1990-2024 violates the Sargent-Wallace prediction at standard significance, and whether inflation, JGB yields, and JPY trade-weighted index remained within non-crisis bands across the period.

Interpretation

Verdict is inconclusive (data gaps) — 2 metric(s) cannot be evaluated because the underlying data source is not yet in the vintages pipeline, and 0 metric(s) have data but a threshold expression the auto-evaluator does not recognise (complex conditions, discrete event counts, cross-country gaps). Close these gaps then re-run.

Steelman live concerns

See hypotheses/steelman/fiscal_dominance_japan_debt_non_crisis.md for the strongest opposing arguments. Canonical-case multi-metric evidence is a pattern match, not a causal identification — the result card should be read as 'outcome trajectory matches the predicted pattern to degree X' rather than 'policy P caused the outcome'.

Provenance

Vintages pinned in manifest.yaml. Full per-metric diagnostics in diagnostics.json. Machine-readable results in metric_results.parquet.

Strongest opposing argument

Every hypothesis ships with its charitable opposing argument. The framework earns credibility by handling objections at their strongest, not weakest.

Notes

Promoted on 2026-04-30 with the original metric thresholds intact. Remaining follow-up: secure a registered fetcher for BoJ governance / monetary independence index, and pin the qualitative coding rule for the monetary-independence metric (which is the weakest leg of the multi-metric design). Note overlap with japan_public_debt_solvency_inflation_independence hypothesis; this spec is the post-Keynesian-framed version testing the Sargent-Wallace prediction directly.

Authored framework. Read the transparency note.