Via negativa, subtraction beats addition
This is documented history rather than a laboratory result. The events are well recorded. What they teach is an argument, and the entry makes it openly.
For most of medical history, doctors made patients worse by adding things. Bloodletting, mercury tonics, elaborate interventions, all confidently applied, many actively harmful. One of the single largest improvements in survival came not from adding a treatment but from removing a contamination. In 1847, a physician named Ignaz Semmelweis noticed that mothers were dying of fever in a maternity ward at terrible rates, far more than in a ward staffed by midwives. He worked out that doctors were going straight from performing autopsies to delivering babies without washing their hands, carrying something deadly with them. He ordered handwashing. In his ward, deaths in childbirth fell from around eighteen percent to under two. Nothing was added to the mothers. Something was taken away. His colleagues, offended by the implication, largely rejected him, and he died disgraced, decades before the idea was accepted.
In any complex situation, you rarely know for certain what will work, but you can often know with confidence what is actively hurting, and removing that is the higher-confidence move. This is the opposite of the usual instinct, which is to fix problems by adding, a new tool, a new process, a new layer. Semmelweis removed a cause of death rather than adding a cure. When something is going wrong and you are tempted to pile on solutions, first ask what you could take away, because subtraction is often both safer and more powerful than addition, and it is almost always the thing nobody suggests.
One says do not remove what you cannot explain. The other says that in a system you do not fully understand, removal is the higher-confidence move. The difference is what you know about the thing. Via negativa applies when you can already see it is actively hurting, as Semmelweis could with the unwashed hands. Chesterton applies when it merely looks pointless and you have not yet found what it is preventing. Removing a known harm and removing an unexplained rule are different acts, and only the first earns the confidence.
Source: Documented medical history, Vienna, 1847. The modern framing of the principle: Taleb, Antifragile, 2012.
Nassim Nicholas Taleb, 2012
Where the case for subtraction over addition is made in full. It argues with you, which is the point.
Draw your own card. It does not take long, and it rewards taking your time.