"The first principle [of science] is that you must not fool yourself, and you are the easiest person to fool." - Richard Feynman, winner of the Nobel Prize for physics, 1965.

When Bill Nye ("The Science Guy") publicly changed his mind recently about genetically modified organisms − he now says they "are an important, and perhaps, essential component of modern farming" − many were quick to pounce.

Besides attacking his reasoning and his credentials, some of his critics even alleged - with absolutely no evidence or justification - that Bill's change of position must have involved a payoff by my company, Monsanto.

The simple, innocent truth, however, is laid out plainly in the recently published revised edition of Bill's book "Undeniable: Evolution and the Science of Creation." In a new chapter, Bill explains that after publishing the first edition of the book, in 2014, he "has spent a great deal of additional time investigating the issues surrounding GMFs (genetically modified foods)." His investigation, he explains, included a deeper exploration of the scientific literature, as well as a visit to our company.

"I was not there to be charmed," he comments on that visit. "I was there to see if Monsanto scientists had hard data to address the issues about GMFs and the ecosystems in which they grow. I now believe they do."

In other words, Bill dug deeper into the issue and then recognized he'd been mistaken. And then he had the courage to admit it.

Who else has trod this path? Well, lots of people. After all, to err is human, and scientists and those who, like Bill, study and write about science, are human. For science to move ahead, therefore, it's critical that the people who pursue it be willing to recognize and correct their mistakes. Otherwise science - and humanity - get stuck.

I know I've made mistakes as a scientist - for example, in being slow to recognize the seriousness of climate change. When the data documenting this trend became overwhelming, however, I studied it - and shifted my position - because I knew that for a scientist, the real sin is not in making a mistake, but in refusing to acknowledge it. That's all Bill has done in this case.





And that puts him in some very good company.

Thomas Edison, for example, famously had to work his way through thousands of failures to achieve some of his great technological inventions.

"I have not failed," he once said. "I have just found 10,000 ways that won't work."

That attitude is typical among great scientists. They know that, as Niels Bohr said, "An expert is a man who has made all the mistakes which can be made in a very narrow field."

Albert Einstein was one such expert. As a recent article in Scientific American shows, the greatest physicist of the 20th century made several important mistakes. But as the article also shows, he was not unwilling to admit it, most notably in connection with his general theory of relativity, introduced in 1915.

Consistent with the prevailing belief of the time, Einstein assumed then that the universe was static - neither expanding nor contracting. That circumstance, however, was a problem for him, because gravity dictated contraction. So the great man inserted into his calculations a "cosmological constant" - a fudge factor he thought was needed to ensure a universe in balance.

Some years later, however, evidence began to mount that the universe was not in balance, that it's actually expanding. So Einstein withdrew the constant - and called it "the biggest blunder he ever made in his life."

My final example of mistakes made and acknowledged concerns Stephen Hawking, the British astrophysicist who comes closest, perhaps, to being Einstein's successor in today's world. Hawking, who helped create modern black-hole theory among countless other contributions, is best known to the public as the author of A Brief History of Time and the subject of the movie, "The Theory of Everything."

Like Einstein, Hawking has admitted some big mistakes. My favorite concerns time:

A few decades ago, some of the world's leading theorists speculated that if the expansion of the universe were to reverse itself and things would begin to contract, time's arrow would flip. Instead of pointing forward, it would run backwards, like a movie in reverse. People, if they still existed, would live from the grave to the cradle.

Now, as spectacular as that thought is, what is almost equally spectacular to me is that for a while, Stephen Hawking believed it. Yes, the man who is arguably the smartest person in the world thought time would reverse - which I gather means the Beatles would reunite, the Great Depression would quickly be followed by World War I, and my St. Louis Cardinals would have another chance at winning the 1985 World Series, which they would have won the first time but for a terrible call by the umpire.

But I digress. As The New York Times reported years ago, Hawking has now "announced that he had changed his mind. Recent research had led him to conclude that time would still march forward, even if the universe began to contract, he told a conference in Chicago on astrophysics."

So too bad for Beatles fans, but good for science. That's how it works. We all have blinders and we all make mistakes, so we keep studying. And when the evidence tells us we've been wrong, we admit it.

Just like Bill Nye did.