Account for Proportionality Bias: Big Events Must Have Big Causes

Holland & Hart - Persuasion Strategies

Holland & Hart - Persuasion Strategies

The current global coronavirus pandemic is a huge disruption to life in nearly every country and the explanations for it have gotten to the point that they’re as big as the disruption. Rather than believing that a virus in Southern China simply transitioned from an animal to a human host, many believe that it must be a planned release as part of a global conspiracy of epic proportions. There is a reason why these kinds of grand explanations can be appealing. Rob Brotherton, an academic psychologist at Barnard College and author of the book Suspicious Minds: Why We Believe Conspiracy Theories (2017) was interviewed in an issue of NewScientist in 2016 on what is called “proportionality bias.” Comparing the many conspiracy theories stemming from the assassination of John F. Kennedy in 1963, to the very few theories formed in response to the attempted assassination of Ronald Reagan in 1981, Brotherton notes that the difference is that the Reagan attempt had little consequence, so required little explanation (a single insane individual will suffice), while the Kennedy assassination had tremendous consequence, and therefore required a proportionally large explanation (not a single criminal, but a massive national conspiracy). “When something big happens, we tend to assume that something big must have caused it,” Brotherton explains. “This is the proportionality bias.”

The same bias applies to thinking about the coronavirus: It is so big, and so disruptive, that it can only have a big explanation. Proportionality bias is the root of conspiracy thinking like this, but is also at the root of more common thoughts about causation. The existence of an extremely significant injury in a civil suit, for example, motivates the search for a big and comprehensive cause. The bigger the injury and the associated damages, the harder it is for people to content themselves with the belief that it simply “happened” with no one to blame. A proportionately big cause (in the form of the plaintiff’s liability theory) may be a more appealing counterweight to a big injury and damages. In this post, I’ll discuss the role of proportionality bias in jurors’ thinking on causation, and share a couple ideas on addressing it. 

A Root of Conspiracy Thinking

While there are many contributors to conspiracy thinking, one of the major psychological factors that makes it appealing is proportionality bias. In a review of the current psychology literature, researchers from University of Kent in the UK (Douglas, Sutton, & Cichocka, 2019), argue that conspiracy theories are used to satisfy psychological motives, including desires for understanding, certainty, control, and self-image. It is a cognitive response to our natural human search for patterns.

It is in this search for patterns that proportionality bias plays a role. The bias “means that small, mundane explanations for important events (e.g., that Princess Diana dies because the driver of the car was drunk) are not as satisfying as larger and more elaborate explanations (e.g., that she was murdered by the British government).”

Motivation for Attributing Large Causation

Conspiracy thinking can play a role in civil litigation. Anti-corporate bias, for example, can take on conspiratorial tones in the form of perceived plans based on deception and greed. But more commonly, proportionality bias applies to thinking about causation, with jurors implicitly wanting to balance the scales between a big result and a big cause for that result. For defendants who want to address that tendency to magnify causes, I can see a couple of routes to try.

Call Attention to the Bias

It is not a perfect cure, but in some situations, awareness of a bias can help people protect themselves against it. For example, in a medical case, raising that awareness could sound something like this:

Everyone agrees, the injuries in this case are significant. And it is only human that when an injury is this large, we want to find something similarly large to explain it. Our brain seeks out that proportionality. We want to believe that only something significant and elaborate could have brought about a result like this. And that can make the plaintiff’s complex liability theory appealing. But in medicine, big consequences don’t always have big causes. The human body is already complex enough, and a state of good health is already, and unfortunately, precarious enough that sometimes bad events simply happen. 

Make Alternate Causes Proportionally Larger

The reality, however, is that it isn’t always possible to get people to set aside their biases because they’re not recognized as “biases,” but are simply our background ways of thinking. The additional answer is to adapt to the proportional mindset by framing the alternative cause as something bigger. For example, you may want to claim that the consequences of a breach of contract were brought about, not by the plaintiff’s attributed complex corporate plot, but by market forces. In that case, it will help to make “the market” not just a background factor in your story, but a major player with its own layers of complexity and even motivation. By making that cause proportionally larger, you are providing an alternative that will be more satisfying to jurors who expect that big events will have big causes.


Douglas, K., Sutton, R. M., & Cichocka, A. (2019). Belief in conspiracy theories: Looking beyond gullibility. Social Psychology Textbook. DOI10, 9780429203787-4.

Image credit:, used under license

DISCLAIMER: Because of the generality of this update, the information provided herein may not be applicable in all situations and should not be acted upon without specific legal advice based on particular situations.

© Holland & Hart - Persuasion Strategies | Attorney Advertising

Written by:

Holland & Hart - Persuasion Strategies

Holland & Hart - Persuasion Strategies on:

Reporters on Deadline

"My best business intelligence, in one easy email…"

Your first step to building a free, personalized, morning email brief covering pertinent authors and topics on JD Supra:
*By using the service, you signify your acceptance of JD Supra's Privacy Policy.
Custom Email Digest
- hide
- hide

This website uses cookies to improve user experience, track anonymous site usage, store authorization tokens and permit sharing on social media networks. By continuing to browse this website you accept the use of cookies. Click here to read more about how we use cookies.