The False Cause Fallacy: How a Generation of Doctors Was Fooled

In 1843, a deadly debate raged among physicians: what caused childbed fever? This devastating illness struck women within days of giving birth, claiming the lives of over 70% of those infected. One prominent obstetrician, Charles Meigs, believed he had the answer: abdominal inflammation. He observed that patients with inflammation often developed the fever, leading him to conclude that inflammation caused childbed fever. But Meigs fell victim to a common logical trap: the false cause fallacy.

Understanding the False Cause Fallacy

The false cause fallacy, also known as post hoc ergo propter hoc (Latin for "after this, therefore because of this"), assumes that because one event follows another, the first event must have caused the second. In simpler terms, it confuses correlation with causation.

• Correlation: Two things happen together.
• Causation: One thing directly causes another.

Just because two events occur in sequence doesn't automatically mean one caused the other. There might be a coincidental relationship, a reverse causal relationship, or a shared underlying cause.

Why Correlation Doesn't Equal Causation

To illustrate this, consider the example of hair growth and tooth growth in babies. Babies typically grow hair before they grow teeth. However, it would be absurd to claim that hair growth causes tooth growth. The two are simply correlated due to the natural stages of infant development.

Similarly, with childbed fever, the inflammation observed by Meigs might have been a symptom of the fever, not the cause. Or, both inflammation and fever could have been triggered by a common, yet unknown, factor.

Alternative Explanations and the Importance of Skepticism

Dr. Oliver Wendell Holmes, a contemporary of Meigs, proposed a different theory. He noticed a pattern: doctors who performed autopsies on women who died of childbed fever were more likely to transmit the illness to their subsequent patients. Holmes didn't immediately conclude that autopsies caused the fever. Instead, he hypothesized that doctors were unknowingly carrying an invisible contaminant from the autopsy room to the delivery room.

This idea was met with resistance, particularly from doctors like Meigs who considered themselves infallible. However, Holmes's hypothesis, unlike Meigs's flawed argument, opened a path for further investigation.

The Breakthrough: Contagion and Disinfection

Ignaz Semmelweis, a Hungarian physician, took Holmes's hypothesis to heart. In 1847, he implemented a mandatory hand-washing policy in his clinic, requiring medical personnel to disinfect their hands after performing autopsies and before examining patients. The results were astounding: the mortality rate from childbed fever plummeted from 12% to just 1%. Semmelweis had proven the contagious nature of the disease.

Later, in 1879, Louis Pasteur identified the culprit behind many cases of childbed fever: Hemolytic streptococcus bacteria.

The Takeaway: Question Everything

The story of childbed fever serves as a powerful reminder of the importance of critical thinking and skepticism. It demonstrates how easily we can fall prey to the false cause fallacy and how crucial it is to consider alternative explanations before drawing conclusions. By questioning assumptions and demanding evidence, we can avoid repeating the mistakes of the past and pave the way for genuine progress.

Don't let flawed logic cloud your judgment. Always remember: correlation does not equal causation.