The Overton window describes the range of policy ideas that are politically acceptable at a given time. In the Dutch parliamentary context, we operationalise this by measuring centrist support for motions at varying levels of policy extremity. The core question is not whether extreme motions pass, but whether centrist parties are willing to support them at all — a signal that a policy position has entered the realm of acceptable debate.
We model acceptability using a gravity framework: each motion is assigned a gravity level (M1 through M5) based on its combined stylistic and material extremity. Higher gravity levels correspond to more extreme motions. The formation of the Schoof cabinet in July 2024 serves as the watershed. By comparing centrist support before and after this date, we can measure whether the Overton window shifted — and if so, by how much.
Each motion was scored on two independent dimensions by an LLM-based classifier: stijl (rhetorical extremity, 1–5) and materieel (policy impact, 1–5). The gravity level is derived from the combined scores. Centrist support is measured as the fraction of centrist parties that voted in favour. The canonical definition uses 4 strict centrist parties: D66, CDA, CU, and NSC. A broader all-party model (including VVD, BBB, and other non-extreme parties) is shown for comparison.
The dataset contains 29,591 motions. The pre-2024 period (January 2016 to June 2024) covers 21,695 motions; the post-2024 period (July 2024 to present) covers 7,875 motions. Mean stylistic extremity: 1.36 (on a 1–5 scale). Mean material extremity: 2.12. The Pearson correlation between the two dimensions is r = 0.43, confirming that style and substance are separable but moderately related.
Centrist support (all-party definition) by gravity level, before and after July 2024. As expected, higher gravity levels show lower centrist support. The post-2024 window shows increased centrist support at levels M3 and above, consistent with a rightward shift in the Overton window.
Using the strict centrist definition (D66, CDA, CU, NSC), centrist support values are lower across all gravity levels, as expected. The strict model isolates the behaviour of the ideological centre without dilution by adjacent parties.
Three motions illustrate different patterns in the Overton window shift.
This motion proposes external processing of asylum procedures outside the EU. It scores stijl = 1 (neutral legal language, no rhetorical escalation) but materieel = 4 (fundamental policy reform). The modest stylistic framing masks the substantive ambition. The strict centrist support (cs_strict) rose from 0.00 pre-2024 to 1.00 post-2024 — a motion that no centrist party would touch before the Schoof cabinet became universally acceptable after.
This motion calls for withdrawing from the 1951 Refugee Convention. It scores stijl = 5 and materieel = 5 — maximum extremity on both dimensions. Despite the broader post-2024 shift in the Overton window, strict centrist support remained at 0.00 both before and after the watershed. Some positions remain outside the window of acceptability regardless of the political climate.
This motion proposes measures for voluntary return of Syrians. It scores stijl = 2 and materieel = 3 — moderate on both dimensions. Strict centrist support went from 0.00 pre-2024 to 1.00 post-2024. This motion exemplifies the category of proposals that crossed the acceptability threshold after the political watershed, gaining full support from the centrist core where it previously had none.
Annual strict centrist support for motions at gravity level M3 and above. Years 2016–2018 have very low motion counts and should be interpreted with caution.
| Year | Count (M3+) | CS strict | Change |
|---|---|---|---|
| 2016 | 17 | 0.705 | — |
| 2017 | 9 | 0.664 | -0.041 |
| 2018 | 12 | 0.958 | +0.294 |
| 2019 | 851 | 0.336 | -0.622 |
| 2020 | 1,157 | 0.308 | -0.028 |
| 2021 | 1,229 | 0.329 | +0.021 |
| 2022 | 1,199 | 0.313 | -0.016 |
| 2023 | 1,099 | 0.355 | +0.042 |
| 2024 | 1,252 | 0.487 | +0.132 |
| 2025 | 1,101 | 0.451 | -0.036 |
| 2026 | 404 | 0.297 | -0.154 |
Comparing centrist support for motions proposed by right-wing parties (PVV, FVD, JA21, SGP) versus motions from all other parties, before and after July 2024.
N: 1,911 pre · 1,119 post
N: 17,768 pre · 8,772 post
Right-wing motions saw a substantial increase in centrist support after the 2024 watershed, rising from 0.384 to 0.620 — a gain of 0.236 points. In contrast, centrist support for motions from other parties remained essentially flat (0.587 pre vs 0.581 post). This asymmetric shift is the central finding of the analysis: the Overton window moved primarily on the right flank, with centrist parties becoming more willing to support proposals originating from the right wing, while their behaviour toward other party motions did not change.
Each cell shows the count of motions at each combination of rhetorical extremity (stijl) and policy impact (materieel), with the percentage of the total dataset. The highlighted cell marks the highest concentration. The Pearson correlation between the two dimensions is r = 0.43.
| Stijl \ Materieel | 1 | 2 | 3 | 4 | 5 |
|---|---|---|---|---|---|
| 1 — Lowest | 6,010 20.31% |
11,428 38.62% |
3,194 10.79% |
391 1.32% |
19 0.06% |
| 2 | 442 1.49% |
2,852 9.64% |
2,880 9.73% |
580 1.96% |
47 0.16% |
| 3 | 100 0.34% |
360 1.22% |
542 1.83% |
308 1.04% |
61 0.21% |
| 4 | 14 0.05% |
46 0.16% |
96 0.32% |
111 0.38% |
49 0.17% |
| 5 — Highest | 2 0.01% |
2 0.01% |
7 0.02% |
32 0.11% |
18 0.06% |