Qualy #65 - The three laws of medicine — Law #1： A strong intuition is much more powerful than a weak test
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Summary
In this episode of The Qualies, Dr. Peter M. Diamond talks about one of the most seminal ideas in medicine, The Laws of Medicine, and how it can apply to any area of our lives. He also discusses the importance of the Bayes-Baysian law, and the role it plays in understanding the universe.
Transcript
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welcome to the qualies a subscriber exclusive podcast qualies is just a shorthand slang for
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a qualification round which is something you do prior to the race just a little bit quicker
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to release quali episodes in the main feed which is what you're about to hear now if you enjoy these
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subscribe so without further delay i hope you enjoy today's quali i want to talk about another book you
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wrote that doesn't get as much attention which is the laws of medicine you wrote that after emperor
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before the gene correct that's right so laws of medicine has a very different mandate as it were
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and that's because the book came out in association with ted they had commissioned 10 books by 10 thinkers
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around the world and they asked me to write a book on that and i it's it's necessarily a small book
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it's really a you know the mandate was to write basically a 75 page book expanding on a single
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very very incisive idea so that's the laws of medicine yes if i if i got them correctly the three
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laws are a strong intuition is much more powerful than a weak test how did you think of that and what
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is the most important application of that law to the way you think about medicine or specifically
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oncology today this to me is one of the great neglected ideas in medicine perhaps one of the
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great neglected ideas in the world this idea initially comes from thomas bayes this is a bayesian
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idea thomas bayes was a cleric but by evening he was a mathematician and an economist and he led his
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work leads to one of the most seminal and funny thought experiments that i've ever encountered which
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is the following and i i sometimes quiz my my daughters with it which is the following this is not thomas
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bayes's own example but it arises out of thomas bayes's work and he one might imagine going to a
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street fair and encountering a man who's tossing coins and he tosses coins and your job is to predict
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whether the next flip coin flip is going to be heads or tails and so he tosses the coin 20 times and all
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20 times its tails so then he turns to the crowd and he says what's the next coin flip going to be heads
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or tails now the mathematician in the crowd who's the professor of mathematics says 50 percent says
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50 percent and you know everyone says absolutely right but the child in the crowd says no no you
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don't understand this is a stupid problem it's the coins rigged the coin has only it has two heads or
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two tails as case may be and the child's right and what's important about that insight is that the
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mathematician imagines the world this in this case this is not a stab at mathematicians in general
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but the professor of mathematics thinks of the world as having no history as having no a priori's
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it's a world that's created de novo every time the coin is flipped and its heads and tails equal every
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time but the child knows and all humans know that in fact the world doesn't behave like that everything
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has priors and you need to understand those priors before you can understand the posteriors there's
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wisdom in that idea and it took someone like thomas bayes to figure that out that most of our lives we
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aren't living our lives like the crazy mathematician professor we are living our lives like the child
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we're thinking to ourselves what was the prior antecedent imagine this is true for any corner of your life
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the first question you ask yourself when you're trying to solve a problem trying to understand the
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cosmos trying to understand something you ask yourself what was the prior like did the sun set in the
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west last night and how about the night before and maybe i don't need to create a formula to figure out
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whether the sun is going to set on the west or the east tomorrow it's because it's set on the west every
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time there are obviously loopholes and gaps to this kind of thinking there are surprises that you can
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miss so bayes's fundamental idea was that you can only interpret a test in the light of what that test
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is predicted in the past it's an extraordinarily important idea in the way we think about about the
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universe that the past performance of a test tells you something not everything but tells you something
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about the future performance of a test and you can apply it to many many things in the world you can
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apply to any kind of thinking economic economic thinking climate change oriented thinking that the past
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is a guide to the future not only in a kind of loose way but you're really using a real stat
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weighted strongly by the past and this of course applies to medicine and it's a forgotten rule
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in medicine although it does seem like one of the things that i've always felt physicians innately
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do well without realizing it which is the opposite of where i want to be not to take the pot shots but i think
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where we do very poorly is in understanding asymmetric risk i hope you enjoyed today's quali now sit tight
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for that legal disclaimer this podcast is for general informational purposes only and does not
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constitute the practice of medicine nursing or other professional health care services including
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the giving of medical advice and note no doctor patient relationship is formed the use of this
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information and the materials linked to the podcast is at the user's own risk the content of this
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podcast is not intended to be a substitute for professional medical advice diagnoses or treatment users should
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not disregard or delay in obtaining medical advice for any medical condition they have and should seek
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the assistance of their health care professionals for any such conditions lastly and perhaps most
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importantly i take conflicts of interest very seriously for all of my disclosures the companies i invest
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in and or advise please visit peter atia md.com forward slash about