None of us are born with the ability to systematically weigh evidence or evaluate complex arguments, but learning these skills will have a profound impact on our personal and professional lives.
By Paul Cerrato, MA, senior research analyst and communications specialist and John Halamka, M.D., Diercks President, Mayo Clinic Platform
You’ve probably heard it said: A little knowledge is a dangerous thing. The astronomer Neil deGrazze Tyson said it more eloquently: “One of the great challenges in life is knowing enough to think you’re right, but not enough to know you’re wrong.” The singer/songwriter Paul Simon expressed it another way: “A man hears what he wants to hear and disregards the rest.” Considering this tendency to focus most of our attention on facts and theories that support our preconceived view, as healthcare professionals, we have an obligation to remain openminded in the face of contradicting evidence.
One place to start this journey is to 1) concentrate on basic principles of logic, 2) develop a healthy skepticism, and 3) be willing to say: I don’t know. To illustrate the need for logical analysis, suppose we are trying to determine if an environmental substance may be contributing to a certain disease. We usually start by collecting observational data to see if more patients with the disorder were exposed to the chemical than were healthy persons, but it’s also important to determine if exposure to the chemical occurred before patients contracted the disease. If event A—exposure to the environmental substance—occurred before patients developed the disorder—B—it may suggest that A contributes to B. If the reverse were true and most patients with the disorder were exposed to the chemical long after they developed the condition, that weakens the argument.
Equally important is the realization that correlation does not equal causation. Even if far more patients with the disease were exposed to the chemical than were healthy persons and that exposure occurred before the onset of the disease, that doesn’t establish a cause/effect relationship. The sick patients may have had other risk factors that contributed to their condition.
Skepticism is another critically important trait for anyone seriously interested in finding the best healthcare solutions. The internet and social media are awash with conspiracies about what causes cancer, heart disease, and a variety of other conditions. That probably explains why the publishers of the Oxford English Dictionary declared the term “brain rot” the word of the year in 2025. The Guardian explained it’s “a term that captures both the specific feeling of mindlessness that descends when we spend too much time scrolling through rubbish online and the corrosive, aggressively dumb content itself, the nonsense memes and AI garble.”
On the subject of humility and willingness to say “I don’t know,” an editorial published in JAMA refers to Evidence Based Medicine’s Six Dangerous Words, words that are often used by healthcare professionals who find it difficult to say I don’t know. Those six words are: “There is no evidence to suggest.” If used recklessly, they can do more harm than good and only serve as a convenient way to dismiss a treatment approach that a clinician is unfamiliar with or that has not been proven with several randomized clinical trials. As R. Scott Braithwaite, MD, with New York University points out, absence of evidence is not evidence of absence. Such unwarranted certainty can conceal the lack of certitude of experts and “may deny treatments with potential benefit” that are supported by large observational studies, clinicians’ clinical experience, mechanism of action data, and animal research. The take home message here is to find a way to strike a balance between randomized double-blind trials and other forms of credible evidence.
Of course, uncertainty about medical science can also be used by unscrupulous actors to mislead the public. The tobacco industry’s playbook for denying the danger of cigarettes is a prime example of this kind of manipulation. As we explained in an earlier publication, doubt is crucial in science—what we call healthy skepticism—because it moves science forward. But it also makes science vulnerable to misrepresentation, because it is easy to take uncertainties out of context and create the impression that everything is unresolved. This was the tobacco industry's key insight: that you could use normal scientific uncertainty to undermine the status of actual scientific knowledge. Individual clinicians cannot single-handedly combat this kind of anti-science, a climate that has only been fostered by some public figures and by the social media. But at the very least, we can make our patients aware of the forces at play and the mind games that such merchants of doubt employ.
Any conversation about critical thinking would be incomplete if it didn’t discuss ChatGPT and other generative AI systems. Do they enhance or inhibit our ability to evaluate medical evidence? A recent experiment performed by MIT scientists suggests that relying on ChatGPT to write a report interferes with a person’s ability to analyze information, causing users to stop questioning statements that they read and leading to fewer original ideas, a condition the researchers refer to as “cognitive atrophy.” They sum up their findings by saying: “The integration of LLMs into learning environments presents a complex duality: while they enhance accessibility and personalization of education, they may inadvertently contribute to cognitive atrophy through excessive reliance on AI-driven solutions…. Prior research points out that there is a strong negative correlation between AI tool usage and critical thinking skills, with younger users exhibiting higher dependence on AI tools and consequently lower cognitive performance scores.”
On the other hand, experts who have studied human creativity have found that working with a chatbot as a thought partner that helps you “examine reasoning pathways” and helps you challenge assumptions and explore uncertainty has merit and will likely sharpen your critical thinking skills.
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