The Truth About Creating Policy: It Can't Be Evidence-Based

Research in cognitive sciences is dictating that we can no longer rely on the presentation of scientific facts when building policy.

3 minute read

November 19, 2017, 1:00 PM PST

By Steven Snell @Stevenpsnell


Public Comment

stock_photo_world / Shutterstock

You're up there presenting to council the policy you just developed. You're confident in your baby: it's evidence-based, after all. You probably even wrote that in your report. You did your background research, accumulated and consolidated information. You poured over it and whittled down the data into tight policy statements. You completed what's considered the "problem-oriented approach" to writing policy. There was a gap, a problem. You resolved it. That's what your policy is based on. It's likely a failure.

Recently, a paper in the Policy Sciences journal used research in cognitive sciences to more fully understand the multifaceted nature of developing policy. The authors, Cairney and Weible, convey that the evidence-based approach to policy development does not consider the "too-messy link between cognitive and contextual explanations for action."

We've long understood that there's a limit to what we can research to develop policy. Only recently, state Cairney and Weible, have we begun to draw on social and organizational psychology to understand how emotions act as informational short cuts and coexist with cognition. We're learning the importance of group processes in leveraging emotional decision-making over rational thought.

A policy scientist analyzing the literature in her field of research may understand its various dimensions and produce recommendations based on it, but the myriad contexts, including her own (ir)rationality, in which the policy is contextualized cannot be fully considered. This should be expected. As Cairney and Weible state, "Our value orientations change following interactions with people who reinforce or challenge our beliefs." We frame our research and are led by those principles as we prioritize the goals of our research.

The authors continue: "A policymaker's environment consists of a myriad of actors and factors: multiple policymakers and influencers spread across levels and types of government; the formal and informal institutions that guide their actions at each level; the networks they form; the ideas of beliefs that dominate the ways in which they think about problems and solutions; the biophysical and socio-economic conditions to which they respond; and the events that offer opportunities and shocks."

What's the result? The authors suggest its tempting to assume we know what makes our audience tick, but policy operates in a context outside the influence of any one person; it's influenced by the crowd. There are many ticks. Thus there's a balance between the rational need of evidence and irrational reality of where decisions about policy are made. We should be making "good enough" decisions in our policy prescriptions. We don't need to seek a rationally perfect depiction of reality.

"If people engage emotionally with information, there is no way to appeal to all audiences with the same information." What are the lessons for developing policy? We're storytellers. Policy authors should tell a simple story with a clear moral, be trustworthy and consider the power structures of politics. We should accept that developing policy is ultimately an output of irrationality (read, political). It isn't an objective relay of evidence.

Ultimately, the authors conclude, "the choice is not whether or not to focus on skillful persuasion which appeals to emotion, but how to do it most effectively while adhering to key ethical principles. Generating trust in the messenger and knowing your audience may be more important to success than presenting evidence."


Steven Snell

Steven Snell has over ten years of professional urban planning experience with a focus on conservation policy. He has a master’s degree in urban design and is a novelist of How Soon We Fall From Love.

"Planetizen federal action tracker" logo superimposed over black and white image of US Capitol dome.

Planetizen Federal Action Tracker

A weekly monitor of how Trump’s orders and actions are impacting planners and planning in America.

October 28, 2026 - Zachary Whalen

A car drives through a puddle, making a large splash. Rain pours down.

California plans to bury El Niño’s downpour

If the state plays its cards right, it may be able to store a billion acre-feet of El Niño’s water in aquifers.

October 28, 2026 - Grist

Lake Powell with much of the water evaporated.

Desperate measures: Advocates weigh draining Lake Powell to fill Colorado River

Draining the reservoir could reduce evaporation losses by a couple hundred thousand acre-feet.

October 30, 2026 - Yale Environment 360

Nithya Ramen talks to an older man. She is smiling and wearing a yellow dress. They are both outside.

Los Angeles just elected an urban planner as its mayor

Transportation analysts are optimistic that Raman will be more aggressive in addressing transit issues than Bass.

November 7 - Los Angeles Times

Mamdani behind a microphone, in front of a snowbank

Mamdani’s pied-à-terre tax survives legal challenge

A panel of judges found that the plaintiffs failed to demonstrate injury as a result of New York City's implementation of the tax.

November 6 - CNN

A road in north eastern Nebraska with power lines on either side, and grassy fields.

Eastern Nebraska is running out of electricity

Data centers and electrification are straining eastern Nebraska’s grid, throttling economic development.

November 6 - Grist

FREE Course: Walkable City 1: Why Walkability?

After describing his path towards focusing on walkability as the essence of good planning, Jeff Speck marches through his five principal reasons for making more walkable places.

Reinventing Malls: Planning Alchemy—Turning Gray Fields Into Gold

The course focuses on the opportunities and imperatives that shape reinvention of mall sites.

Write for Planetizen