Should-Read: The late Zvi Griliches—who had taught Robert Lucas—once said to me that he had found Lucas a good technician and a very hard worker, but that he worried about Lucas as someone influential enough to set intellectual fashions.
A case in point. It would not have been that hard for Lucas to discover what "crossing over" of chromosomes was, would it?
And, yes, I do think it has had a bad effect on the advance of knowledge:
A Professional Memoir: "There was nothing spooky about Mendel’s genetic theories...:
...They were clear, they made some kind of sense (though there was nothing molecular in our Nat Sci II readings), you could work out predictions that would surprise you, and these pre-dictions matched interesting facts. We did a classroom experiment with fruit ‡ies, focused on eyes, and pooled the results. Our assignment was to write up the results in a lab report and compare them to predictions from a Mendelian model. I had not enjoyed the actual lab work but I liked writing the report and spent the better part of my weekend on it. It was the first time I can recall ever working out the predictions of a scientific theory from its basic principles and testing these predictions against experimental evidence.
On Sunday evening, my friend Mike Schilder returned to the dorm from a week-end that had clearly not been occupied with fruit flies. The report was due Monday, and he asked to copy mine. I agreed, in part just to get some reaction to a report that I was very pleased with.
Mike came back in half an hour, and told me: “This is a good report, but you forgot about crossing-over.” “Crossing over” was a term introduced to us to describe a discrepancy between Mendelian theory and certain observations. No doubt there is some underlying biology behind it, but for us it was presented as just a fudge-factor, a label for our ignorance. I was entranced with Mendel’s clean logic, and did not want to see it cluttered up with seemingly arbitrary fudge-factors. “Crossing over is b—s—,” I told Mike.
In fact, though, there was a big discrepancy between the Mendelian prediction without crossing over and the proportions we observed in our classroom data, too big to pass over without comment. My report included a long section on experimental error, describing the chaotic scene that generated the data and arguing that errors could have been large enough to reconcile theory and fact.
I handed it in as written. Mike, on the other hand, took my report as it stood, except that he replaced my experimental error section with a discussion of crossing over. His report came back with an A. Mine got a C-, with the instructor’s comment: “This is a good report, but you forgot about crossing-over.”
I don’t think there is anyone who knows me or my work as a mature scientist who would not recognize me in this story.
The construction of theoretical models is our way to bring order to the way we think about the world, but the process necessarily involves ignoring some evidence or alternative theories—setting them aside. That can be hard to do—facts are facts—and sometimes my unconscious mind carries out the abstraction for me: I simply fail to see some of the data or some alternative theory. This failing can be costly and embarrassing to me, but I don’t think it has any effect on the advance of knowledge. Others will see the blind spot, as Mike did with crossing-over, keep what is good and correct what is not.