One of the greatest scientific duels in history occurred between those who believed that microorganisms spontaneously generate in decaying organic matter and those who believed that the tiny creatures migrated there from the open air. From the late 1850s to the late 1870s, the eminent French chemist and microbiologist Louis Pasteur was locked in a death-match with proponents of spontaneous generation, especially Felix Pouchet.
The two camps performed experiments one after the other, both to prove their pet theory and to disprove the opponent's. As we know, Pasteur won the debate: The fact that microbes travel through the air is now accepted as a given, with spontaneous generation relegated to the slag-heap of quaint, discarded scientific ideas. But Pasteur didn't win fair and square.
It turns out that some of Pasteur's experiments gave strong support to the notion that rotting organic matter produces life. Of course, years later those experiments were realized to have been flawed, but at the time they buttressed the position of Pasteur's enemies. So he kept them secret.
In his myth-busting book Einstein's Luck, medical and scientific historian John Waller writes: “In fact, throughout his feud with Pouchet, Pasteur described in his notebooks as ‘successful’ any experiment that seemed to disprove spontaneous generation and ‘unsuccessful’ any that violated his own private beliefs and experimental expectations.”
When Pasteur's rivals performed experiments that supported their theory, Pasteur would not publicly replicate those studies. In one case, he simply refused to perform the experiment or even discuss it. In another, he hemmed and hawed so long that his rival gave up in exasperation. Waller notes: “Revealingly, although Pasteur publicly ascribed Bastian's results to sloppy methodology, in private he and his team took them rather more seriously. As Gerald Geison's study of Pasteur's notebooks has recently revealed, Pasteur's team spent several weeks secretly testing Bastian's findings and refining their own ideas on the distribution of germs in the environment.”
Pasteur would rail at his rivals and even his mentor when he thought they weren't scrupulously following the scientific method, yet he had no qualms about trashing it when doing so suited his aims. Luckily for him, he was on the right side of the debate. And just why was he so cocksure that spontaneous generation was wrong? It had nothing to do with science. “In his notes he repeatedly insisted that only the Creator-God had ever exercised the power to convert the inanimate into the living,” writes Waller. “The possibility that life could be created anew without man first discovering the secrets of the Creator was rejected without any attempt at scientific justification.”