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Navigating the Uncertain: A Book Review of “The Laws of Medicine”


Siddhartha Mukherjee, MD, provides a framework to reconcile the uncertainties we constantly experience in our practice of medicine in his book, "The Laws of Medicine."

Great books provide avenues to comprehend the sensory and cognitive overload that we’re often subjected to. I’ve frequently turned to “The Laws of Medicine, by Siddhartha Mukherjee, MD, for treading this path.


During residency, the author was looking for ways to reconcile the uncertainties he constantly experienced in the practice of medicine, and was inspired by a collection of essays by Lewis Thomas, “The Youngest Science,”  and the foundations were laid for the laws he discusses in his own book.


One of Mukherjee’s main points is that even though medicine is considered a science, it lacks laws that other fields of science possess. The author tracks the arc of medicine, and then weaves together interesting clinical encounters that have shaped scientific breakthroughs with ones that have personally influenced him, to conceive his three laws.


Law One – A strong intuition is much more powerful than a weak test.

Our differential diagnoses have varying degrees of probability associated with them. We employ tests to push one of these differentials into the realm of certainty. However, many of these tests are imperfect. Prior knowledge (or intuition) helps us interpret these tests better and influences these diagnostic probabilities. A classic example is the prostate specific antigen (PSA) test. Interpret it without context and it will lead us down the path of a multitude of unnecessary investigations. But add more elements such as family history, risk factors, genetics, or a change of PSA value over time into the mix, and its ability to adjudicate further investigation increases.


Law Two – “Normals” teach us rules; “Outliers” teach us laws.

The author illuminates examples ranging from astronomy to autism to show that even though we can establish patterns from studying the vast majority, it’s the outliers that have the potential the upend these patterns. Just like an analysis of a dramatic responder in a trial employing everolimus for advanced bladder cancer paved the way for understanding genetic influences on the dreaded condition.


Law Three – For every perfect medical experiment, there is a perfect human bias.

The very fact that human beings are part of research, whether designing it or by being a subject, is a harbinger for bias. The main endeavor of studies is generalization; however, much research falls short – women are historically underrepresented in randomized trials, as are female mice in laboratory studies.


We constantly seek a blueprint to understand the various nuances of medicine and can feel disorientated in the absence of the same. These laws can be that initial map to aid that pursuit for both the fledgling and the established practitioner.


My search for the laws was not an attempt to codify or reduce the discipline into grand universals. Rather, I imagined them as guiding rules . . .

~ Siddhartha Mukherjee, MD