by Ueli Reber, Karin Ingold and Christian Stamm
Swiss lawmakers have debated pesticide regulation for nearly a decade, often drawing on different types of scientific and policy evidence to support their positions. In Reber et al.’s recent study, the authors analyse how problemoriented evidence (highlighting environmental or health risks) and solutionoriented evidence (emphasising policy effectiveness) were used strategically in parliamentary discussions.
Analysing parliamentary texts with computational methods
To study this, the authors compiled a corpus of 1,738 parliamentary documents — including written requests and plenary debate transcripts — containing references to pesticides. Using keyword searches, they retrieved 10,642 paragraphs. They then applied finetuned transformerbased text classification models to each paragraph to classify (1) the position expressed — either in favour of policy change (“change”) or defending existing policy (“status quo”) — and (2) whether the paragraph invoked evidence, and if so whether that evidence was problemoriented (highlighting risks) or solutionoriented (emphasising the effectiveness or sufficiency of existing or alternative policy measures).
Distinct patterns: Who uses what type of evidence — and when
The results show systematic differences between proponents and opponents of pesticide regulation. When actors called for change, they invoked evidence in about onethird of relevant paragraphs; when defending the status quo, evidence appeared less frequently. More strikingly, proponents overwhelmingly used problemoriented evidence (about 67%) to highlight environmental and health risks of pesticides, with fewer relying on solutionoriented evidence (about 33%). By contrast, defenders of current policy used solutionoriented evidence slightly more often (50.6 %) than problemoriented evidence (49.4 %) — suggesting that when arguing against change they emphasised the adequacy of existing regulation or questioned the necessity or feasibility of alternative measures.
Shifting discourse over time: Triggering events and “knowledge creep”
A particularly revealing finding is a temporal shift in the evidence strategy of status quo defenders. Until 2017, their resistance to change more often involved problemoriented evidence — for instance, emphasising the benefits of pesticide use (like high yields or farm productivity). But from 2018 onwards, there was a clear pivot towards solutionoriented evidence: actors increasingly argued that existing legislation sufficed or that proposed reform measures would be ineffective or disruptive. The authors link this shift to the entry into parliamentary debate of two popular initiatives calling for a broad ban on synthetic pesticides — a political “trigger” — as well as to the gradual accumulation of empirical knowledge about pesticide risks (socalled knowledge creep), which made outright denial of environmental or health hazards less tenable.
Implications for evidenceinformed policymaking and policy change
This study makes several important contributions for scholars of evidence use and policy change. First, it shows that evidence is not used uniformly — the type and frequency of evidence invocation depend on actors’ positions and strategic context. Second, by using a longitudinal approach, the authors demonstrate that evidence use is dynamic: political triggers and the growth of knowledge shape how evidence is mobilised over time. Third, the distinction between problem and solutionoriented evidence reveals how debates shift from contesting problems to contesting solutions — or contesting the adequacy of existing solutions — a dynamic central to understanding policy inertia, stasis or incremental change.
For the Swiss case, this suggests that even opponents of pesticide regulation gradually adapted their rhetoric as knowledge about environmental and health risks became harder to ignore. Rather than denying the problem, they reframed their arguments around the sufficiency of existing measures — a rhetorical shift that may help explain why legislative change remained incremental rather than radical.
For researchers interested in evidenceinformed policymaking more broadly, the article underscores that evidence is not simply a neutral input: it is a strategic resource, selected and framed differently depending on political aims, institutional context, and evolving empirical knowledge.
In summary, Reber et al. offer a rigorous, datadriven analysis of how knowledge shapes policy discourse — reminding us that what counts as “evidence” in political debate depends not only on facts, but also on strategy, timing, and institutional incentives.
You can read the original research in Policy & Politics at
Reber, U., Ingold, K., & Stamm, C. (2025). Patterns in the use of problem- and solution-oriented evidence in legislative discourse: the case of pesticide policy in Switzerland. Policy & Politics (published online ahead of print 2025) from https://doi.org/10.1332/03055736Y2025D000000082
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Hill O’Connor, C., & Bennett, H. (2025). Lived experience as evidence in anti-poverty policy making: a governance-driven perspective. Policy & Politics (published online ahead of print 2025). Retrieved Feb 25, 2026, from https://doi.org/10.1332/03055736Y2025D000000078
Piddington, G., MacKillop, E., & Downe, J. (2024). Do policy actors have different views of what constitutes evidence in policymaking?. Policy & Politics, 52(2), 239-258 from https://doi.org/10.1332/03055736Y2024D000000032
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