Making science too simple

At LSE, one of my lectures remarked, “The problem with Popper and Hempel is they try to make things too simple.”

In particular, the idea of a decisive experiment that conclusively falsifies a theory does not do justice to the complexity of what actually goes on in scientific research. There are almost always multiple ways that one can sensibly take some experimental result. For instance, I am reading The Eighth Day of Creation at present. The author describes how, in 1944, Oswald Avery and colleagues published a paper that offered evidence that the carrier of genetic information was a nucleic acid. The author himself considers the paper to of offered “rigorous proof“ that this was the case, but when he talks to other scientists, it becomes clear that the author is mistaken. at the time of the experiment, the reigning theory held that nucleic acid‘s were too simple to carry the genetic information. Given this, Max Delbrück tells him there were at least three reasonable ways to interpret the experiment: 

1. Avery had simply made a mistake in his experimental procedure. 
2. The nucleic acid‘s did not carry the genetic information, but somehow flipped a switch in proteins, which at the time were thought to be the carrier.
3. The current theory about nucleic acids was wrong, and they really did carry the genetic information.