One of my favorite books is Demon-Haunted World by the legendary astronomer, educator and author Carl Sagan. Hailed as a “spirited defense of science” by the Los Angeles Times, the book debunks popular fallacies that abound in the world of pseudoscience.

In Chapter 12, “The Fine Art of Baloney Detection,” Sagan discusses 20 fallacies that often interfere with our ability to properly evaluate “claims to knowledge.”

Absence of Evidence

Sagan’s fourth fallacy – “Appeal to Ignorance” – offers defense attorneys valuable insight into a jury’s mindset.

There are two components to the “Appeal to Ignorance” fallacy:

1. A lack of proof that something is true does not necessarily mean it’s false. To express this notion, Sagan coined the phrase “absence of evidence is not evidence of absence.”
2. If something has not been proven false, it must be true. Sagan offered the following example, highlighting the fallacy: “There is no compelling evidence that UFOs are not visiting the Earth; therefore UFOs exist.

If you’re a defense attorney with experience in toxic tort or drug/medical device litigation, you’re all too familiar with this fallacy.

In civil cases involving allegations of personal injury from a product or chemical exposure, the burden of proof rests on the plaintiff. The plaintiff’s goal is to demonstrate that the product or exposure caused the injury. The defense’s strategy is to point out the lack of valid scientific evidence linking the product to the injury (i.e., “absence of evidence”).

But every defense lawyer knows it’s not enough to cite the lack of reliable studies showing a causal relationship. Why? Because jurors buy into Sagan’s fourth fallacy: a lack of proof that something is true does not necessarily mean it’s false.

The Holy Grail

At the end of the day, the defense must prove that the product or exposure did not cause the injury because if something has not been proven false, it must be true. The defense attorney knows he or she must present “evidence of absence.”

But there’s a problem. Technically, science does not permit the demonstration of “evidence of absence.” Let’s say we have 100 epidemiological studies evaluating whether drinking orange juice in the morning is associated with brain cancer, and they all fail to find a link. One could still posit that a link exists, claiming that the studies were not comprehensive enough or were poorly designed.

However, if a plethora of studies fail to find a link between an exposure and an injury, scientists are more willing to support the view that “evidence of absence” exists. Indeed, sometimes absence of evidence does equal evidence of absence. Practically speaking, the more null findings that arise, the more scientists are willing to support the view that there is evidence of absence. We discussed this philosophical conundrum in a guest blog post we did with our good colleague Nathan Schachtman.

Another approach to exonerating a product or exposure is to present other potential causes of the injury.

Other Sagan Fallacies and Tools

In addition to “Appeal to Ignorance,” the other 19 fallacies Sagan describes in Chapter 12 also offer valuable insight for defense attorneys. Some of the more prominent fallacies are as follows:

• Ad hominem attacks
• Argument from authority
• Begging the question, also called assuming the answer
• Observational selection
• Post hoc, ergo proper hoc (“it happened after, so it was caused by”)
• Confusion of correlation and causation

Also in Chapter 12, Sagan offers a boloney detection tool-kit, a profound and valuable set of tools that can be used to effectively evaluate the scientific legitimacy of an argument.

A rigorous and logical evaluation of the facts will always lead to the correct conclusion. As Sagan states, “The question is not whether we like the conclusion that emerges out of a train of reasoning, but whether the conclusion follows from the premise or starting point and whether that premise is true.”

Did you like this post? We are here to help! Schedule a consult with one of our experts.

Just fill out the form bellow and we will contact you with more information.