**Data:** 2,850 classified right-wing motions in the Tweede Kamer, 117 dual-scored for 2D extremity, Procrustes-aligned SVD party positions across 10 annual windows
**Data:** 2,869 classified right-wing motions with 2D extremity scores (96% of all 2,986), Procrustes-aligned SVD party positions across 10 annual windows, MP-level vote records for centrist parties (D66, CDA, ChristenUnie, NSC)
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@ -33,6 +33,34 @@ The migration domain is the primary vehicle. Migration motions gained +0.233 in
A critical methodological note: **pass rate is useless as an indicator.** Dutch parliament passes 96%+ of motions in both periods. With near-zero variance, pass rate cannot register a shift of any magnitude. Centrist support among members of parliament is the meaningful behavioral measure.
### Domain Decomposition
The aggregate shift masks two distinct stories. Breaking the data by policy domain reveals where the Overton window genuinely shifted and where right-wing moderation explains the change:
| Domain | Pre CS | Post CS | Pre M≥4% | Post M≥4% | Pattern |
**Non-migration (85% of motions):** The story is clear strategic moderation. Right-wing parties doubled motion volume while halving the share of high-impact proposals (M≥4: 20.8%→8.0%). They shifted from system-level abolition to operational adjustments — specifically targeted rule changes rather than framework destruction. Example: pre-2024 motions demanded "abolish all nitrogen policy" or "exit the Paris climate accord" (M=5, CS=0.0 every time). Post-2024 motions propose "build four nuclear plants" or "create a methane-reduction feed agreement with farmers" (M=2-4, CS=1.0). Centrists rewarded the operational framing.
**Migration (15% of motions):** The pattern is different. Material impact barely changed (3.26→3.13, only −0.13), yet centrist support more than doubled (0.153→0.369). Crucially, centrists went from *never* supporting M=5 migration motions (CS=0.000) to backing nearly 1 in 5 (CS=0.185). The gradient between impact levels flattened significantly — centrists still differentiate, but the gap narrowed. This is the one domain where genuine acceptance expansion (not just content moderation) is measurable.
### Who Drove the Shift? MP-Level Granularity
The shift is not uniform across centrist parties. Counting individual MP votes on right-wing motions:
The two Christian-conservative parties — CDA and ChristenUnie — more than doubled their migration vote share. D66, the secular-progressive centrist party, barely moved from a very low baseline. NSC, formed in 2023 with migration as a defining issue, entered at a high level. The shift is not "centrists accepting right-wing content" — it is "the Christian-conservative wing of the center moved substantially, while the progressive wing barely budged." The composition of who counts as "centrist" matters: a five-seat CDA with 40% voor has a different political meaning than a 24-seat D66 with 10% voor.
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## Indicator 2: SVD Spatial Drift
@ -90,6 +118,17 @@ The dominant pathway is **consensus framing** — right-wing motions that packag
Critically, only one motion among the 24 involved targeted rights restriction, and **zero involved system dismantling.** The truly ideological right-wing agenda — asylum stops, treaty exits, fundamental institutional upheaval — does not gain centrist support. Right-wing influence flows not through converting centrists to right-wing positions, but through repackaging: speaking the vocabulary centrists already accept.
### Anti-Institutional Motions: From Abolition to Contestation
Anti-institutional motions — those targeting courts, treaties, the constitution, or the EU — show the same strategic pivot:
- **Treaty challenges:** shifted from "pull out" (Vluchtelingenverdrag opzeggen) to "block ratification" or "explore modifications"
- **Judiciary criticism:** 2 → 8 (increased, but focused on specific policies: abolish judicial dwangsommen, limit anonymous testimony, constrain judicial review scope — working within the system)
The pattern is consistent across domains: right-wing stopped proposing to abolish institutions and started proposing to adjust specific rules within them. The volume of explicit institutional attacks declined, and what remains operates within rather than against the system. Centrist support for even the softened anti-institutional motions remains low (average CS=0.3), confirming these remain partisan territory.
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## The Overton Window Verdict
@ -106,7 +145,9 @@ What changed post-2024 was not what centrists found acceptable — it was what r
4. **SVD divergence confirms this interpretation.** Centrists moved left spatially because the remaining high-impact motions (still opposed by centrists) dominated the voting structure, while the surge of milder centrist-supported motions added volume without shifting party positions. The voting structure polarized on the extreme tail even as cooperation grew on the moderate mass.
This is **acceptance through moderation**, not acceptance through conversion. The Overton window — the range of politically acceptable policy — did not expand rightward. Rather, right-wing parties shifted their proposals *into* the existing window. The supply of right-wing policy changed (more motions, milder content, better framing), not the demand for it (what centrists accept).
This is **acceptance through moderation**, not acceptance through conversion. The Overton window — the range of politically acceptable policy — did not expand rightward in most domains. Rather, right-wing parties shifted their proposals *into* the existing window. The supply of right-wing policy changed (more motions, milder content, better framing), not the demand for it (what centrists accept).
**With one exception: migration.** The asylum/migration domain shows a pattern distinct from all others. Material impact barely declined (−0.13), yet centrist support more than doubled. Centrists went from zero support for M=5 migration motions to nearly 20%. The gradient between impact levels flattened. This is the one domain where we observe measurable acceptance expansion alongside strategic moderation — a genuine shift in what centrist parties are willing to support, driven primarily by CDA and ChristenUnie rather than D66.
### Uncertainty Hierarchy
@ -115,8 +156,11 @@ This is **acceptance through moderation**, not acceptance through conversion. Th
| **Strong** | Centrist voting support surged (d = +0.65 strict, d = +0.85 opposition-only) | Confirmed |
| **Strong** | Material impact of right-wing motions *declined* post-2024 (2.78→2.43, M≥4 share: 23.7%→11.3%) | Confirmed on n=2,850 |
| **Strong** | SVD spatial divergence — centrists moved left, right moved further right | Confirmed |
| **Moderate** | Strategic moderation: right-wing increased volume of milder proposals | Supported by material impact trend + mechanism analysis |
| **Moderate** | Dominant mechanisms: consensus framing and institutional language | Based on n=24 motions; classification is qualitative |
| **Strong** | Migration domain: centrist M=5 support went from 0.0 to 0.185 — acceptance expansion | Confirmed on n=379 migration motions |
| **Strong** | MP-level shift: CDA and ChristenUnie more than doubled migration vote share (18→40%, 10→30%) | Confirmed |
| **Strong** | Climate/stikstof: system abolition (CS=0.0) replaced by operational proposals (CS up to 1.0) | Confirmed |
| **Moderate** | Strategic moderation in non-migration domains: volume up, material impact down | Consistent across 2,471 motions |
| **Inconclusive** | Whether extreme content genuinely declined or was repackaged in milder language | 2D scoring separates style from substance, but temporal content shift unmeasured
