# The Laws of Medicine ## Metadata * Author: [Siddhartha Mukherjee](https://www.amazon.com/Siddhartha-Mukherjee/e/B003SNL6EA/ref=dp_byline_cont_ebooks_1) * ASIN: B00WFOQ20Q * ISBN: 978-1476784847 * Reference: https://www.amazon.com/dp/B00WFOQ20Q * [Kindle link](kindle://book?action=open&asin=B00WFOQ20Q) ## Highlights “It’s easy to make perfect decisions with perfect information. Medicine asks you to make perfect decisions with imperfect information.” — location: [56](kindle://book?action=open&asin=B00WFOQ20Q&location=56) ^ref-46044 --- But all this information could, I soon realized, be looked up in a book or found by a single click on the Web. The information that was missing was what to do with information—especially when the data was imperfect, incomplete, or uncertain. — location: [68](kindle://book?action=open&asin=B00WFOQ20Q&location=68) ^ref-33958 --- I had never expected medicine to be such a lawless, uncertain world. I wondered if the compulsive naming of parts, diseases, and chemical reactions—frenulum, otitis, glycolysis—was a mechanism invented by doctors to defend themselves against a largely unknowable sphere of knowledge. The profusion of facts obscured a deeper and more significant problem: the reconciliation between knowledge (certain, fixed, perfect, concrete) and clinical wisdom (uncertain, fluid, imperfect, abstract). — location: [78](kindle://book?action=open&asin=B00WFOQ20Q&location=78) ^ref-43706 --- 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 that a young doctor might teach himself as he navigates a profession that seems, at first glance, overwhelmingly unnavigable. The project began lightly—but it eventually produced some of the most serious thinking that I have ever done around the basic tenets of my discipline. — location: [195](kindle://book?action=open&asin=B00WFOQ20Q&location=195) ^ref-29428 --- I’m describing this case in such detail because it contains a crucial insight. Every diagnostic challenge in medicine can be imagined as a probability game. This is how you play the game: you assign a probability that a patient’s symptoms can be explained by some pathological dysfunction—heart failure, say, or rheumatoid arthritis—and then you summon evidence to increase or decrease the probability. Every scrap of evidence—a patient’s medical history, a doctor’s instincts, findings from a physical examination, past experiences, rumors, hunches, behaviors, gossip—raises or lowers the probability. Once the probability tips over a certain point, you order a confirmatory test—and then you read the test in the context of the prior probability. — location: [235](kindle://book?action=open&asin=B00WFOQ20Q&location=235) ^ref-45011 --- by merely changing the structure of the tested population, the same test is transformed from perfectly useless to perfectly useful. You need a strong piece of “prior knowledge”—I’ve loosely called it an intuition—to overcome the weakness of a test. The “prior knowledge” that I am describing is the kind of thing that old-school doctors do very well, and that new technologies in medicine often neglect. — location: [266](kindle://book?action=open&asin=B00WFOQ20Q&location=266) ^ref-46089 --- If you fail to use prior information, you will inevitably make foolish judgments about the future. This is the way we intuit the world, Bayes argued. There is no absolute knowledge; there is only conditional knowledge. History repeats itself—and so do statistical patterns. The past is the best guide to the future. — location: [301](kindle://book?action=open&asin=B00WFOQ20Q&location=301) ^ref-22623 --- Standard probability theory asks us to predict consequences from abstract knowledge: Knowing God’s vision, what can you predict about Man? But Bayes’s theorem takes the more pragmatic and humble approach to inference. It is based on real, observable knowledge: Knowing Man’s world, Bayes asks, what can you guess about the mind of God? — location: [304](kindle://book?action=open&asin=B00WFOQ20Q&location=304) ^ref-62880 --- Kepler, however, did not consider Mars peripheral: if a planetary model was real, it had to explain the movements of all the planets, not just the convenient ones. — location: [370](kindle://book?action=open&asin=B00WFOQ20Q&location=370) ^ref-49783 He paid attention to the nuances, the unexplained details, in order to come up with a better ' 'truth'' --- Untested and uncontested, a theory became a law: no surgeon was willing to run a trial for a surgical operation that he knew would work. Halsted’s proposition ossified into surgical doctrine. Cutting more had to translate into curing more. — location: [548](kindle://book?action=open&asin=B00WFOQ20Q&location=548) ^ref-58492 --- A randomized study might make particular conclusions about the effectiveness of a medicine—but in truth it has only judged that effectiveness in the subset of people who were randomized. The power of the experiment is critically dependent on its strong limits—and this is the very thing that makes it limited. The experiment may be perfect, but whether it is generalizable is a question. — location: [589](kindle://book?action=open&asin=B00WFOQ20Q&location=589) ^ref-31837 --- Extracting medical wisdom from a randomized study thus involves much more than blithely reading the last line of the study published in some august medical journal. It involves human perception, arbitration, and interpretation—and hence involves bias. — location: [598](kindle://book?action=open&asin=B00WFOQ20Q&location=598) ^ref-2640 --- The greatest clinicians who I know seem to have a sixth sense for biases. They understand, almost instinctively, when prior bits of scattered knowledge apply to their patients—but, more important, when they don’t apply to their patients. They understand the importance of data and trials and randomized studies, but are thoughtful enough to resist their seductions. What doctors really hunt is bias. — location: [605](kindle://book?action=open&asin=B00WFOQ20Q&location=605) ^ref-44601 --- Despite the sophistication of medical technologies, uncertainties have remained endemic to medicine because the projects that medicine has taken on are vastly more complex and ambitious. — location: [623](kindle://book?action=open&asin=B00WFOQ20Q&location=623) ^ref-57353 ---