In a brief search for examples, I found a statement that "moving the goalposts" refers to changing the rules, not changing the goal. For instance, requiring a scientist to submit more or different kinds of evidence than is usually required to prove an idea or theory.

I originally thought "moving the goalposts" was negating a previously held theory. Such as, in medicine, bloodletting. Or in science history, Galileo and Capernicus, and whether the earth revolved around the sun. Also, the world is flat, etc. Now I'm just more confused as to what the original discussion was about.

Also, my Venn diagram/Don's subsumed words: Newton/Kepler->Einstein -- but I can't think of more examples.