Critical Thinking in Medicine

Critical Thinking in Medicine

Most people who choose the health care profession seem to naturally possess empathy,

compassion and altruism. These qualities make us want to deliver quality health care. We share a common goal. Providing health care requires decisions and practices that are valuable to patients. We use information to guide these practices.

Although helping patients toward optimal health is our common goal, we don't always choose our sources of information in a common way. Without a reliable approach to evaluating the sources of medical information and claims, we cannot be certain that we are making the best choices. We owe it to our patients to use the best information available when making decisions about their lives.

Traditionally, we are trained in the clinical art of medicine. The 'art' involves connecting with our patients, communicating effectively, being empathetic and compassionate. The art of medicine involves being thorough, yet concise. It also involves persuasion. In medical training, we become clinical thinkers. However, we receive little (if any) formal training in critical thinking. Yet, the practice of medicine requires critical decision making that can be life-saving if done properly, or dangerous if flawed. Critical thinking is a necessary part of our job and our art. In order to practice this art, we need reliable information.

** The art of medicine is informed by the science of medicine.

During the intense education process, we memorize volumes of facts and consume information. We often take it for granted that this information is correct. We've been taught about the scientific method and know something about the psychological biases that influence our beliefs. Most of us realize that some information is more trustworthy than others. Since we want to deliver the best health care that we can, we need to be equipped with critical thinking skills to help us sort out the good information from the bad, the science from the bunk.

** The critical thinker and modern skeptic lives in a world characterized by shades of grey. There are rarely absolutes. Scientific information is judged on a statistical spectrum of 2 basic types of error. On one end, we have Type 1 Error which is what happens when we accept ideas without good reason. In other words, we accept things that are likely to be false. This is the basic error that characterizes Pseudoscience. Then we have Type 2 Error. Type 2 errors are made when we reject things that are likely to be true. This is the common error made in Denialism and Pseudoskepticism. The skeptical doctor must be careful to avoid such errors if at all possible. We can use science as a tool to help us from drifting too far toward these types of errors. Without it, our biases will prevent us from seeing where we stand on the spectrum of error. Only then can the art of medicine be optimally informed by the science of medicine.

Here, we will learn the basic tools of skepticism and critical thinking. We will scratch the surface of the philosophy of science. We will explore ideas that are practiced today that have no basis in science, yet are still firmly believed. The information on this site will be updated and corrected from time to time, just as science must be updated and corrected from time to time.

Mark Crislip, MD identified some basic problems in medical thinking that can lead to Type 1 and Type 2 errors: "a reliance on anecdotes, using sub-optimal studies as evidence, mistaking a gobbet of basic science as a meaningful clinical application, and not realizing the warping effect of confirmation bias". He also identified what he calls the three most dangerous words in medicine...'In my experience'.

This site aims to help us to identify these errors, not only in others' thinking, but in our own.

Skeptical Medicine: 2 Themes

The running theme throughout this site is that, while our policies and decisions are philosophic in nature, we should use science and reason to inform these policies and decisions. Our reasons for connecting claims to decisions should follow established rules of logic. However, our initial resolution to use science and reason in the first place is purely philosophic. As we make the decision to value science, reason and logic over other "ways of knowing", we ground ourselves in a way of thinking that demands adherence to the rules of science, reason and logic.

** It is logically contradictory - and therefore forbidden - to embrace science and logic when they support an idea, but then to reject them when they do not.

For an expansion of this argument, please refer to the You Can't Have it Both Ways section of this site. However, one may wish to read the sections in order to build core concepts needed for this argument.

Another important theme will be dealt with in detail in the Alternative Medicine and Skeptical and Compassionate sections. This theme observes that science-informed medical practices can be delivered with compassion and humanism. The art of medicine should be informed by the science of medicine. In recent years, many have turned away from mainstream medicine in search of practices that promise care that is 'natural' and 'holistic'; care that is perceived as focusing on the individual and validating individuals as human beings. Academic centers have tried to bring these lost patients back by 'integrating' with so-called alternative medicine practitioners by forming departments of 'integrative medicine'. We do not need to do this to appear compassionate. If the public and institutions think that scientific medicine lacks humanism, then we must learn to change the way that we deliver it.

** It is possible and necessary to deliver science-based medicine with compassion.

How to Use This Site

This site is meant for the health care provider with an interest in critical thinking and science based medicine. The sections are meant to be read like a book. The arguments of the later pages build on premises established in the earlier pages. It starts on a level playing field with a foundation of philosophy. Hopefully, we can see how the bricks are stacked from the foundation to the conclusion.

To embrace the value of critical thinking (in health care or in general) one must start from the point of view of the scientific skeptic. If you, the reader, are already there, feel free to browse the various sections to brush up on logical fallacies, statistics and the various forms of pseudoscience. If you are not already of this point of view, please read the essays 'Philosophy and Science', 'What is Science?', 'What is a Skeptic?' and 'Pseudoscience' first. These essays start with the basics of Philosophy and Science, build on the ideas, and (hopefully) define pertinent topics in an understandable and unambiguous way. The sections on Cognitive Dissonance and Cognitive Biases will help our understanding of why we tend to rationalize unsupported ideas, even in the face of conflicting evidence. The sections on Scientific Studies and Statistics & Risk will hopefully clarify how to put knowledge and data in perspective. Once these concepts are clear, we will then move on to Argumentation & Logic and Logical Fallacies to learn how ideas should - and should not - be presented to others and some of the logical pitfalls used in persuasion.

The sections on Medical Practices Unsupported by Science and Pseudoscience in Health Care highlight practices in common use today despite disconfirming evidence and sound philosophy. In these sections, we will apply the ideas and skills from the previous sections to evaluate medical claims that have been marketed to the public.

Skeptical Medicine is not a blog. However, please feel free to comment on relevant sections and related articles at the Facebook page.

** Note - Key concepts will be preceded by a double asterisk (**).

Author's Comments

My name is John Byrne. I am a doctor of Internal Medicine and Pediatrics in a private practice and I am the creator of this site. The information presented here represents my thoughts and learning as well as the thoughts of the other contributors. It does not necessarily represent the official stances of any institution with which the site's authors are affiliated.

I give special thanks to Andrea Wilkins for her time and expertise in editing this site, and to Sarah Byrne for drawing the "Doctor-Thinker" logo.

If you are a practitioner and/or 'true believer' of unscientific medicine, then this site may do little to change your mind. To quote Jonathan Swift, "(I)t is useless to attempt to reason a man out of a thing he was never reasoned into.". Please read the material anyway. If you keep an open mind, you may gain insight into the skeptic's point of view.

I am learning too. The information here represents my best understanding of the issues discussed. I try to learn from experts from various fields. Access to some of their expertise can be found through the Links section of this site. Other than this paragraph, I will try to refrain from writing in the first person.

References to the relevant journal articles are provided. Also, references to appropriate Wikipedia pages and other sites are provided as well for the reader. I realize that referencing to Wikipedia pages is considered faux pas, but it is the most available reference on the web and each article carries it's own list of direct references which can be further checked. Information referenced on crowd-sourced sites such as Wikipedia should be taken with skepticism. However, factual information pertaining to established science has been found to be on par with traditional encyclopedias (also, see here and here). My goal is to provide references to the most accessible, factual information. Whenever possible, scientific studies are referenced and linked directly to the source journals or to the PubMed entry. There are a tremendous number of citations and I am adding them all the time. Relevant citations are linked directly in the texts as I write about them for immediate verification and further reading.

The costs of health care and the expectations from health care professionals are rising. We should not waste time, effort, resources and money by promoting ideas that are incorrect, dangerous, or both. We have learned to be clinical thinkers. Now we must learn to be critical thinkers. It is time for us to take some skeptical medicine.


John Byrne, M.D.

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