Why “Evidence-Based” Policy Needs Politics Too

Public health professionals are trained to see evidence as the gold standard. The logic seems simple: if research shows what works, governments should act accordingly. Yet, as the authors note, policy isn’t medicine.

In clinical settings, evidence guides treatment for an individual patient. But health policy affects entire populations, and every policy choice reflects competing priorities — economic, moral, and ideological. Policymakers must decide not only what works, but what’s fair and whose interests are served.

Parkhurst and colleagues trace the rise of “evidence-based policymaking” to the success of evidence-based medicine (EBM). While EBM helped eliminate harmful or ineffective treatments, transplanting its linear model to policymaking created unrealistic expectations.

“It is naïvely rational,” they write, “to assume that evidence can simply direct policymaking in a linear way.”

Evidence Use Has Many Faces

One of the most useful takeaways from the chapter is that “using evidence” can mean many different things. Carol Weiss’s classic typology — revisited by the authors — identifies at least seven ways research can inform policy:

• Instrumental use: applying a study’s findings directly to make a decision.
• Conceptual use: shaping how people think about a problem.
• Political use: selectively using evidence to support a preexisting position.
• Symbolic use: invoking “evidence” to lend legitimacy to an agenda.

While instrumental use is the ideal that many public health professionals aspire to, it’s rare. More often, evidence enters policy debates through strategic or symbolic channels — especially when issues are contentious, like vaccination, nutrition, or reproductive rights.

This doesn’t mean evidence is irrelevant. It means that understanding how and why evidence is used—and by whom—matters as much as generating it.

Evidence Is Political — and That’s Not a Bad Thing

One of Parkhurst’s central insights is that health policymaking is inherently political because it involves deciding “who gets what, when, and how.” Competing stakeholders—ministries, industries, NGOs, advocacy groups—each frame problems differently.

For example, rising obesity rates might be framed as:

• A public health crisis requiring regulation;
• A personal responsibility issue emphasizing education; or
• A market opportunity for reformulating the food industry.

Each framing point refers to different “evidence” and different solutions. Recognizing this helps public health professionals avoid frustration when “the data don’t speak for themselves.” They rarely do.

“Evidence use,” the authors argue, “cannot be separated from politics. It must be understood as part of the broader struggle over values, power, and legitimacy.”

Institutions Matter

The chapter also highlights a missing piece in many discussions on “evidence translation”: institutions. Rules, norms, and decision-making structures determine whose evidence counts, when, and how.

Some systems, such as the U.K.’s National Institute for Health and Care Excellence (NICE), formalize evidence use through standardized reviews and advisory bodies. Others rely more on informal relationships and political negotiation. In both cases, institutions “govern” how evidence flows into policy.

The authors describe this as the “institutionalization of evidence use.” Once structures, norms, and expectations are in place, they can either promote transparency and accountability—or entrench biases and hierarchies about what kind of knowledge is considered legitimate.

What This Means in Practice

For local and national health agencies, this research offers practical guidance:

1. Map the Policy Landscape. Before advocating for an evidence-based intervention, identify the political and institutional context. Who holds decision power? What are the existing norms and rules for using evidence?

2. Frame the Problem Strategically. Understand that evidence doesn’t stand alone. Craft your message around values and priorities that resonate with decision-makers and the public.

3. Build Long-Term Relationships. Institutional change requires trust. Establish ongoing partnerships between researchers, policymakers, and community leaders to co-produce and interpret evidence.

4. Strengthen Evidence Systems. Invest in data governance, transparency, and accessibility so that evidence use becomes routine, not reactive.

5. Accept Complexity. Evidence-informed policy is an ongoing process, not a single decision point. Embrace iteration, negotiation, and learning.

What’s Next & Barriers

The authors call for a shift from asking “How do we get evidence into policy?” to asking “How do politics and institutions shape evidence use?”

But barriers remain:

• Power asymmetries: Corporate or political actors may dominate the framing of problems.
• Institutional inertia: Rules that favor certain types of evidence (e.g., randomized trials) can marginalize qualitative or community data.
• Limited capacity: In many low- and middle-income countries, technical staff and data systems are under-resourced.

The book’s global case studies—from Cambodia to Germany—show that these challenges are universal, even if their expressions differ.

Why It Matters

For the public health community, embracing this nuanced view of evidence use doesn’t weaken our commitment to science—it strengthens it. It invites a more realistic, democratic, and context-sensitive approach to policymaking.

In short, evidence-informed policymaking isn’t about removing politics from health—it’s about governing evidence wisely within political systems.

Reflective Questions

• How does your agency define “good use” of evidence?
• Whose voices are included or excluded when evidence is applied to policy?
• What institutional changes could make evidence use more equitable?