The Importance of Doubt in Scientific Thinking

Even though it’s safe to assume that the field of medicine is the epitome of scientific method, ironically, it wasn’t always so. In fact it was the opposite. It was a field marred with arrogance, hubris, and a sheer lack of scientific rigour. Most importantly, what medicine lacked was doubt. Doubt is not a fearful thing and, as we’ll soon learn, it’s in fact what propels science forward.

Galen of Pergamon was a Greek physician, surgeon, and philosopher in the Roman Empire. Considered to be one of the most accomplished of all medical researchers, Galen influenced the development of various scientific disciplines, including anatomy, physiology, pathology, pharmacology, and neurology.

His writings were the indisputable source of medical authority for more than a thousand years. He writes, “It is I, and I alone, who has revealed the true path of medicine”. And yet Galen never conducted anything resembling an experiment.

Experiments are what people do when they aren’t sure what the truth is. Galen didn’t have a shred of doubt in his ‘opinions’. Each outcome ‘confirmed’ he was right, no matter how shoddy the evidence might look to ‘someone less wise than the master’. For example, he declares, “All who drink of this treatment recover in a short time, except those whom it does not help, who all die. It is obvious, therefore, that it fails only in incurable cases.”

Turns out the biggest influencer of the field also suffered from confirmation bias and hubris heavily. In other words, Galen was in love with the smell of his own fart. It’s no wonder that medicine, as we know it, took a while to evolve.

For hundreds of years, physicians had far too little interest in proving what was effective. They didn’t want to let go of the idea that their judgment alone revealed the truth, so they kept doing what they did because they had always done it that way. They didn’t need scientific validation. They just ‘knew’. The had the God complex.

When George Washington fell ill in 1799, his physicians bled him relentlessly, dosed him with mercury to cause diarrhoea, induced vomiting, and raised blood-filled blisters by applying hot cups to his skin. A physician in Aristotle’s Athens, or Nero’s Rome, or medieval Paris, or Elizabethan London would have nodded in agreement at much of that hideous regimen.

Washington died a painful death. One might hope that this would have made the physicians question their methods. But in reality, Washington’s death proved nothing about the treatment beyond that it failed to prevent his death. It’s very much possible that the treatment didn’t help at all, or in fact, it hastened his death. But these concerns were out of the question because the physicians ‘knew’ what they were doing.

If they had any doubts about the treatment, they wouldn’t have prescribed them in the first place, would they? The treatment was effective, it’s just that it wasn’t effective enough. Maybe they should have doubled down on bleeding Washington.

It takes more rigorous experimentation than “bleed the patient and see if he gets better” to overcome misconceptions, and that was never done. Because if there’s no doubt about the efficacy of the current methods, there’s no room for improvement.

The irony is that about 50 years before George Washington’s gruesome death, a cure for this malpractice came very close to a discovery, but was ignored for the next 170 years.

In 1747, when a British ship’s doctor named James Lind took twelve sailors suffering from scurvy, divided them into pairs, and gave each pair a different treatment: vinegar, cider, sulphuric acid, seawater, a bark paste, and citrus fruit, it was an experiment born of desperation, but was also a rudimentary form of clinical trial.

In Lind’s time scurvy was a terrifying disease, estimated to have killed 2 million sailors. It was a mortal threat to sailors on long-distance voyages and not even the confidence of physicians could hide the futility of their treatments. So Lind took six shots in the dark—and one hit.

The two sailors given the citrus recovered quickly. Lind established that a diet of citrus fruit prevented sailors from developing this dreaded disease, although he didn’t realise the significance of his own experiment back then. By the early 1800s, scurvy had become a problem of the past for the British navy, as all its ships took to the seas with an adequate supply of citrus fruit. This is usually the point at which history books end the story, celebrating a great triumph of the scientific method.

But it’s very surprising that this completely preventable disease made an unexpected comeback a century later, when British expeditions started to explore the polar regions. The British Arctic Expedition of 1875, the Jackson-Harmsworth Expedition to the Arctic in 1894, and most notably the two expeditions of Robert Falcon Scott to Antarctica in 1903 and 1911 all suffered greatly from scurvy.

How could this have happened? A combination of ignorance and arrogance. By 1900 the leading physicians in Britain had forgotten the lessons of a century before. Dr. Reginald Koettlitz, Robert Scott’s physician for the Antarctica expedition, attributed scurvy to tainted meat. Further, he added, “the benefit of the so-called antiscorbutics (or scurvy preventatives, such as lime juice) is a delusion.” Why? Because he just ‘knew’.

In his 1911 Antarctica expedition, Scott stocked dried meat that had been scrupulously inspected for signs of decay but no citrus fruits or juices. The trust he placed in the doctor’s opinion contributed to the tragedy that followed. All of the five men who made it to the South Pole died. One team member turned back before the pole and made it back alive, but with a severe case of scurvy.

Not until the twentieth century did the idea of careful measurement of results and scientific rigour take hold in the field of medicine. Not until the British statistician (not a physician) Austin Bradford Hill laid out a template for modern medical investigation using Randomised Control Trials (RCT) in the 1920s.

If patients who were identical in every way were put into two groups, and the groups were treated differently, he wrote, we would know if the treatment caused any difference in outcome. It seems simple but is impossible in practice because no two people are exactly alike, not even identical twins, so the experiment will be confounded by the differences among test subjects.

But randomly assigning people to one group or the other would mean whatever differences there are among them should balance out if enough people participated in the experiment. Then we can confidently conclude if the treatment caused any differences in observed outcomes. It isn’t perfect. There is no perfection in our messy world. But it beats the hubris of wise men stroking their chins.

For centuries, medicine wasn’t science but, what Richard Feynman calls, cargo cult science. It looked liked science, but there was no scientific rigour behind the regimen. It was too cocksure. It lacked doubt.

When the scientist tells you he does not know the answer, he is an ignorant man. When he tells you he has a hunch about how it is going to work, he is uncertain about it. When he is pretty sure of how it is going to work, and he tells you, “This is the way it’s going to work, I’ll bet,” he still is in some doubt. And it is of paramount importance, in order to make progress, that we recognise this ignorance and this doubt. Because we have the doubt, we then propose looking in new directions for new ideas. The rate of the development of science is not the rate at which you make observations alone but, much more important, the rate at which you create new things to test.

— Richard Feynman, The Meaning of It All

Doubt is the essence of scientific thinking. When you don’t have doubt, you don’t measure. What you cannot measure doesn’t get better.

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