Jason Crawford

And Koch was saying that bacteria were responsible for cholera.

And Pettenkofer decided to disprove this.

He was so convinced that, you know, just the bacteria alone were not the cause of cholera that he actually drank a bunch of cholera bacteria in a demonstration to prove that, you know, this theory is ridiculous.

Somehow he survived.

We don't totally know how.

Seems like maybe he had a mild case of cholera or maybe it had some sort of pre-existing immunity.

But that's how, you know, how convinced he was.

So you might wonder, well, how do these people make any progress at all if they had the wrong theory?

Well,

They had a sort of right theory.

They had a theory with some truth or possibility to it.

They also had empirical correlations.

So ever since the 1700s, people have been trying to collect data and just form empirical correlations between certain conditions of the environment and disease.

And they had noticed that certain kinds of filthy conditions were related to disease, and that was correct.

Also, by the way, evolution endowed us with a sense of smell and a sense of disgust, which to a first approximation are not bad ways to kind of avoid disease.

And so some of these early reformers were driven as much by aesthetic sense as by health considerations.

They wanted – and in fact, the early efforts to clean up the water were driven by taste, smell, color, things that you can directly perceive and that your natural sense of sort of cleanliness or aesthetics is going to guide you in basically the right direction.

But it can only guide you so far.

And what happened was eventually – so we were able to clean up the water somewhat.

But eventually when we got the germ theory and that had been really established and proven –