Skip to Main Content

We have a new app!

Take the Access library with you wherever you go—easy access to books, videos, images, podcasts, personalized features, and more.

Download the Access App here: iOS and Android


It has been said that man is a rational animal. All my life I have been searching for evidence which could support this.

—Bertrand Russell

*Mr. Ketterman's Care

Mrs. Ketterman wants to know what I think of the recommendation from Mr. Ketterman's physician to initiate a glutamate pathway modifier as a treatment for his Alzheimer's disease. She knows that I see many patients with Alzheimer's disease in my practice. (See Appendix for Mr. Ketterman's health history.)

In this chapter, we will examine some important questions that health care practitioners should consider before stating a diagnosis or prognosis. Embedded in each diagnosis or prognosis are a number of assumptions, possibly shared, between the clinician and patient. In addition, there may well be biases that serve to undermine the accuracy of the prognosis, biases that may work entirely subconsciously on the clinician. In Chapter 2 we described two ways in which clinicians typically make decisions:

  • the classic differential diagnosis known as hypothetico-deductive reasoning, or

  • the expert's ability to use pattern recognition as a shortcut to a diagnostic or intervention decision.

Neither one of these decision making styles or other types of clinical reasoning is wrong in and of themselves, but each can lead to faulty reasoning and errors in judgment. Biases, defined as inaccurate beliefs that affect decision making,1 coupled with any clinical reasoning strategy can result in errors. Can we ever free our clinical reasoning of biases? While the answer to that question is unavailable, we do know that if we do not recognize our biases, we cannot work to avoid their negative impact on our decision making. Let's examine the case example of Jack Watson.

*Case Example—Jack Watson

Jack Watson, a 64-year-old patient with a history of left knee pain, has returned to his orthopedic surgeon in December for the fourth time in 6 months. His pain had appeared without warning the previous March, following a day when he put much greater strain on his knee than usual. A long-time weekend warrior, Jack played his usual strenuous Saturday morning game of tennis, proceeded to spend 3 hours weeding in his garden that afternoon, and then decided to try out some new hamstring-stretching exercises he had heard about from his tennis partner. With his first step the following morning, he had acute left knee pain, and it has continued to a greater or lesser degree ever since.

Jack had a mild case of polio at the age of 9, with modest muscle loss in his back and legs. While his musculoskeletal system no doubt compensated for this muscle loss in a variety of ways throughout his life, Jack nevertheless has been able to remain quite active physically. He played varsity tennis in college, continued to play tennis throughout his adult life, jogged regularly starting at the age of 48, and has led a generally active life for ...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.